Rebuilt engine today - Runs for 1 second then stops won't stay running [Archive] - GrandAmGT.com Forum

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BigTom209
03-11-2012, 11:41 PM
So I bought a '03 Grand Am with a blown headgasket, was able to drive the car into the shop and tore the motor down and redid everything, got it all back together tonight and tried to start it and you turn the key, can hear the fuel pump going then stops once pressured, cranks... starts... and then maybe after running for a second it completely shuts off. Sometimes it coughs or maybe backfires at the very end so I'm thinking/guessing the fuel is being cut off.

Tried starting it probably 5+ times each time the exact same results just starts and runs for a second then quits.

No check engine light... hooked up a code reader and didn't see any pending codes... everything looks like it should work?


So I'm stumped. Did I miss a sensor that if not hooked up the engine wouldn't run? Any ideas? Since it was running fine (minus the cloud of white smoke out the tailpipe) before rebuilding the engine I must of missed something...

unchained_01
03-11-2012, 11:48 PM
crank sensor wire or crank sensor itself they get brittle from the heat also check all the plugs going to the maf , map and aic they can get bent over and you wont notice , also bleed the fuel rail and see if you have pressure

KillNThrill24
03-11-2012, 11:53 PM
chances are your not gonna get a check engine light right after you put it back together... i rebuilt mine and for 3 days had no engine light... and then it came back. i would be terribly concerned if that thing ever went off lol

you should go back over the engine tomorrow (the fresh start ALWAYS helps believe me) and maybe youll find something you missed. it could be something simple like you forgot to connect the injectors, or forgot to re connect the lines to the fuel rail.. or simply forgot to plug in a connector for the coil packs. there are a ton of connectors on the back of the engine (none of mine are attached to their brackets i routed them the way it suited best for me) so dont get too stressed about it, im sure its nothing horribly wrong unless you forgot to put the rocker arms and push rods in >_<

BigTom209
03-12-2012, 12:00 AM
crank sensor wire or crank sensor itself they get brittle from the heat also check all the plugs going to the maf , map and aic they can get bent over and you wont notice , also bleed the fuel rail and see if you have pressure


Crank sensor, that's the one located below the power steering pump?

What should I look for, just if it looks like broke wires or something else? I did check them over once or twice to make sure they were plugged in, but didn't look overly close besides that

unchained_01
03-12-2012, 09:42 AM
Yes Are you sure your getting spark and fuel ? I would also check the plug at the Injector harness

BigTom209
03-12-2012, 10:13 AM
I must be getting spark/fuel if it's starting and running for a second. I pulled the fuel rail and injectors when I rebid the top end so there was zero fuel pressure before hand. I could see maybe an issue with the crank sensor causing the issues but damnit I don't want to pull that power steering pump back out!!! ;crap

PSKpsu
03-12-2012, 10:23 AM
Yah sounds like a cranksensor to me. and it will not throw any codes since the PCM has to do a cycle to see if all the sensors are working or not. normally the car has to warm up and enter closed loop for a pre-set amount of time. even then the MIL light still might not come on unless it's emissions related.

BigTom209
03-12-2012, 05:05 PM
Update:

I'm back at the vehicle, I removed the power steering and looked at the connector it seemed fine and locked in, I removed it, checked with a ohm meter all 3 pins of the connector back to the big plug up near the alternator and there is connection, so the wire from the plug to the big plug (only like 1 foot long) is fine. All cables from there on seem free and not pinched so that seems good. I put di-electric grease on the connectors and re-seated them and tried the car, exactly the same runs for a second then stops. I unplugged the crankshaft sensor, left it unplugged and started the car and again ran exactly the same.

I don't have a gauge to measure the fuel pressure on the rails, but the pump is definately pumping some since when I press the center pin on the pressure tap on the fuel rail it does squirk out a fair bit of fuel, then turn the key to prime it again and more fuel comes out.

I also tried leaving the key in the on position for over 10min, some suggested it maybe the security but I have some doubts since I drove in with this key. have tried a different key, and after the engine starts/dies the security light on the dash goes out... on my Impala (slightly newer) when I got a new ignition put in the key wouldn't even turn over the car it would just blink the security light until the new one was reprogrammed. So I'm somewhat doubtful of the security being the problem even though it acts alot like it.


Suggestions? I'm still stumped and there isn't a car part dealer anywhere near here to get a new crank sensor to try out... is there anyway to test the old one??

BigTom209
03-12-2012, 05:26 PM
Another question for you guys, the one located directly under the power steering pump, that's the cam position sensor... everyone says it sounds like the crank position sensor... where is it located then?

The one I've been playing around with I guess is the cam sensor... so maybe I'm looking at the wrong thing? I pulled the sensor out and looking online it's definitely the cam.

AaronGTR
03-12-2012, 06:16 PM
The sensor below the PS pump is the cam position sensor, not the crank sensor. There are two crank sensors, one on the back of the block which is the 7x sensor, and one behind the crank pulley which is the 24x sensor. The PCM uses all three of those for the main control of fuel injector and ignition timing. If the cam sensor or 24x crank sensor has a problem, it can run in a default mode if at least two of the three are working, and one has to be the 7x sensor. It won't run without that. And if the cam sensor is bad, you have a 1:6 chance of the injectors being timed for the correct cylinder.

If there is a problem with any of those sensors though, you'll get a check engine right way since they are vital sensors. You don't have to wait through any cycles for those. So it sounds to me like your problem is somewhere else. Possibly the security feature cutting off fuel... although I don't know why it would if you didn't change the computer, and you should still get a security light or code in the PCM.


I guess I should ask... when you say you rebuilt the engine, what does that mean? IE how much did you take off and what did you replace? Did you Disassemble the whole block and everything, or just take the heads and everything off down to the block in order to replace the head gaskets? And another very important question, are you sure you put the push rods back in the correct order? There are different lengths for the intake and exhaust valves, and if you mix them up the engine won't run, and you'll likely bend them.

MMGT1
03-12-2012, 08:11 PM
Aaron is onto something there with the push rods I think. Did you remove rockers when you had the heads off? You may have rockers that have backed off as well. If they have, it'll show on a compression test. You'll see nothing on the intake or exhaust stroke meaning valve is just staying open. If you dont get any compression on one or more cylinders, then pull the covers and check the rockers. Again though, the way you've explained it dying, I would suspect the rods

BigTom209
03-13-2012, 09:52 AM
Update:

I found a website that described how to roughly check the crankshaft sensor, ie I only have a multimeter and not a O-scope, anyway the sensor itself tested fine, I didn't check the cam sensor as it didn't say how to do that one... likely similar but anyway I do have a spare 3.4L motor here so I figured I'd spend 10min and swap coil packs to eliminate that possibility. Swapped them out, exact same thing. So shouldn't be the crankshaft sensor (at least the one that plugs into the coil pack directly) and it's not the coil pack.

My brother-in-law came out and was trying to help, one thing I did was while he was in the car I jumpered out the fuel pump relay so the pump would start and keep running while he started the vehicle and it did the same thing so I don't think it's a lack of fuel pressure since this should've kept the pressure up higher then normal even. So put it all back together then he started it did the same thing started then quit... he started it again but fluttered the pedal a bit and the engine kindof ran a bit but sounded rough was misfiring etc, he thought it was a timing issue since he had that happen before when he rebuilt a engine and got a set of plug wires backwards.

But I'm near 100% sure the wires are on right, plus checked google and again I'm sure it's right

1 3 5
2 4 6

Each wire from the coil pack is labelled and the cylinder numbers are on the coil pack so it's just line up the number on the coil to the number on the plug wire and connect to the cylinder....

Anyway he was monkey'ing around a little and in the end pulled the plugs for cylinder 1 and 5 (he wanted to swap those two around but thankfully the wires aren't long enough to reach easily!) anyway we tried starting it and it did roughly the same thing ran for a second then quit... with 2 missing pistons...

So I'm leaning towards 2 scenarios... one being no spark on a cylinder or two which I think is probably not the case but fairly easy to test run a plug wires with spark plugs to ground and turn over the motor and watch. The other which I'm thinking is more likely is I don't have fuel going to all cylinders, be it a plugged injector or broke wire on the connector or a connector not fully seated. I didn't know when I tore the engine down that I could've left the injectors attached to the manifold or I would've left them alone and just removed everything with them attached still. When I connected the injectors back up I did push them in decent and gave each a tug all felt good but maybe it's not fully connected.

Is there anyway to test injectors firing? I don't know how but maybe someone has an idea that doesn't involve removing the upper manifold to get access to them

Starglow
03-13-2012, 11:49 AM
So what about the pushrod & rocker questions being asked? Seems to me like you're side-stepping the direction the more experienced members are pointing you in as the probable cause for some reason. :wtf

AaronGTR
03-13-2012, 05:19 PM
Yeah, you've got the cylinder order correct, so as long as you have the correct wires running from the coil posts to each cylinder that should be fine. Swapping 1 and 5, or any of them for that matter, wouldn't really accomplish anything.

KillNThrill24
03-13-2012, 11:02 PM
i too, didnt know i could leave the injectors attached to the manifold. although it wouldnt have mattered i soaked my manifolds and valve covers over night in degreaser to get all the crap out of them...

stupid question... did attach the connector for the fuel rail itself? IIRC its a green plug that runs through one of the runners on the UIM. if for some reason thats unplugged, id almost guarantee thats your problem.

KillNThrill24
03-13-2012, 11:05 PM
but should all the connections be connected, you may really want to check those rods. they werent just saying it to make your day worse lol

BigTom209
03-14-2012, 09:18 AM
When I removed the rockers/rods I found a separate empty spot on another work bench, took cardboard and drew out a picture of an engine bay with big lettering saying "DO NOT TOUCH", then one by one (ie I wouldn't even take 2 sets at a time) I removed a rocker/rod, and laid it down on the cardboard in the orientation with the picture.

When installing them, I started on the exact same set I removed first and again, one by one I brought them over from the other work bench and installed them. Torqued them to spec, inspected each one as best I could make sure all the keys were in place and everything looked good.

I'm not side-stepping the question Starglow, I never gave it much thought since it's one area I'm sure that's not the problem.

BigTom209
03-14-2012, 09:26 AM
I guess I should ask... when you say you rebuilt the engine, what does that mean? IE how much did you take off and what did you replace? Did you Disassemble the whole block and everything, or just take the heads and everything off down to the block in order to replace the head gaskets?



Just down to the heads. There is no antifreeze in the oil so I wasn't worried about inspecting the rod bearings or changing a oil pump etc plus this car has relatively low KMs so it all should be good minus the head gasket.

BigTom209
03-14-2012, 10:45 AM
Update:

I did get a chance to check the spark for each cylinder, they all seem to be throwing nice spark. So I have spark... I "should" have compression since I just redid the head gaskets if not I'll cry... the rods should not be a problem... I'm still leaning towards fuel and the only thing worked on with that is the injectors.

thoughts?

AaronGTR
03-14-2012, 03:44 PM
I'd say you should borrow, rent, or buy a fuel pressure gauge from somewhere first and make sure you are getting correct fuel pressure at the rail.

BigTom209
03-14-2012, 04:47 PM
What should it be approx, 55 PSI give or take?

AaronGTR
03-14-2012, 09:30 PM
Normal would be 46-48psi with the engine idling. Around 55psi with the engine off or at full throttle.

BigTom209
03-24-2012, 02:36 PM
Well back at the car now so ready to start posting again!


I tried to hunt down a fuel pressure gauge, last time we used one here was a few months ago we just borrowed it from the dealership in town (car is located on a far hours from the city) so I called the dealership in town again to see if I could borrow it and of course this time they say it's their policy for the last number of years not to borrow out tools. :applause: Thanks guys... I even said I borrowed it before and the guy just said whomever did lend it out wasn't supposed to. Nice eh?

So... can't really see accurately the pressure. I did goto my brother-in-laws truck with a 4.8L and pressured it up, and pushed the relief on the fuel rail and saw it shoot out, then went to the car and did the same thing... yes this is not proper but it also shot out fuel pretty good. Plus we also simply pushed the relief valve while turning the key on and fuel was pouring out pretty good.

Is there 40+ PSI? No idea... but there is fuel and there is pressure so for now until I find a gauge I'm going to have to assume it's ok and try anything else I can.


I also took out all the plugs and checked compression, all six were 150-160 PSI so really good and happy with that. Hooked up all 6 plugs and laid them out on the windshield in order and turned the car over all had good spark and although it was tough to tell they seemed to be firing in order...

So, compression... spark... it still seems like fuel issue. Unless there is a problem with one of the cam or crank sensors when the vehicle starts the signal is dropping out or something I don't know. I don't have a O-scope here either to watch the signals while it's running. I'm thinking I need to rip the UIM off and look what's going on... I don't want to but what else can I try? Would really like to get the fuel rail pulled off and somehow actually watch the injectors spraying but I don't think there is enough slack in those hard fuel lines for that. That's my main thought is maybe there is a plugged injector or else the connector is not fully connected and it's not firing properly.

I'm just stumped... it's driving me nuts :(

zukiracer19
03-24-2012, 02:54 PM
crank sensor won't let his car start period.

BigTom209
03-24-2012, 03:41 PM
If I disconnect the crankshaft sensor plug on the coil pack, it turns over without firing at all, if I plug it in, runs for a second etc. Site on the net described how to test it, check ohms should be between 500-900 which is was, and while cranking it over should read around 0.5VDC and I was getting 0.4V

If I had a O-Scope I'd check the waveforms to confirm.

If you know of a better way to test it out let me know

BigTom209
03-24-2012, 06:28 PM
Drove round trip probably total of 1.5hrs to borrow a $500 master fuel pressure kit! That damn kit has more brass fittings and hoses then I've ever seen in my life... hooked it up, turned the key, 60PSI while the pump was running, 55PSI give or take once the pump quit. Started it up and it wobbled between 50-55 for the second or so it was running


So scratch that one off the list. I hated to drive that far to pick it up since I didn't think it was the problem, but at least I can say now it's fine. Would've hated ripping things apart if in the end that was the problem.

Starglow
03-24-2012, 08:37 PM
I assume you checked all ground connections and inspected the wiring harness for possible damage or shorts....correct?

A bad ground or other electrical short would explain why it's only running for a second. It's easy to accidently damage wiring or overlook something when tearing that far into the engine.

Since you have fuel and spark, the only things left are vacuum leak, bad ground, electrical short, or bad PCM.

BigTom209
03-24-2012, 11:27 PM
Well, after getting the fuel pressure checked out the next step was basically start ripping the UIM off and seeing if I could find anything wrong. Well it didn't take long... took the air box off, started removing the throttle/cruise cables and opened the butterfly with my fingers and felt something down the throat... odd... shouldn't be anything in the airway path... shine a light inside... the gasket for the throttle body wasn't on right.

The sh**ty thing is, that was the ONLY thing I didn't do when I was putting things back together... brother-in-law stopped in and was helping me out (He's very mechanical, not a rookie) so I let him tinker getting the TB back together and hooked all up while I worked on other things... and yup the bottom difficult bolt/stud the gasket was on properly but the top/easy one it slid down so the bolt missed it and it was just crooked.

So, took out the top bolt, loosened the bottom one enough to give it some slack, moved the gasket in place and put everything back together... fired right up and seems to be running fine. Drove it up and down the grids a miles, quite a bit of white smoke at first but guessing the exhaust/cat etc likely was full of antifreeze and just needs to heat up and burn off, it was much better by the time I drove around a few minutes and brought it back to the shop.


SO... figured it was something dumb... tested and retested damn near everything... and in the end some stupid little mistake was all it was. Could've happened to anyone, hopeful nothing else goes wrong with this car for a VERY long time!!!

Thanks to everyone for the suggestions and help, I'm just sorry in the end it was user error and kindof a waste of everyones time... especially mine

:cheers:

AaronGTR
03-25-2012, 12:12 AM
huh, well... that's one more reason I don't like other people working on my cars. If I do it, I know it's done correctly. Even if someone is supposedly very mechanical, that's no guarantee they know anything about cars. I've known people who think they know how to fix cars, and really they don't know jack. Anyway...

Next time you need a tool, try checking your local auto parts store and see if they have rental tools. All the stores by me have a tool rental policy in store, where they carry specialty tools and let you borrow them and take a deposit for the tool, then when you return it you get the deposit refunded. They do this because they know people don't have some of those tools, and if they can't do the job and fix the car themselves, they won't buy parts from the store. ;) It's good business.

BigTom209
03-25-2012, 08:39 AM
huh, well... that's one more reason I don't like other people working on my cars. If I do it, I know it's done correctly. Even if someone is supposedly very mechanical, that's no guarantee they know anything about cars. I've known people who think they know how to fix cars, and really they don't know jack. Anyway...

Next time you need a tool, try checking your local auto parts store and see if they have rental tools. All the stores by me have a tool rental policy in store, where they carry specialty tools and let you borrow them and take a deposit for the tool, then when you return it you get the deposit refunded. They do this because they know people don't have some of those tools, and if they can't do the job and fix the car themselves, they won't buy parts from the store. ;) It's good business.



Well, I can't say one way or another in terms of help. It's actually his shop I'm working in and he works on the rigs as a mechanic (not trained just that good and it's a private company so papers aren't as required) plus his main job is farming so he's more mechanically inclined then pretty much everyone I know! And that says something since my dad was a GM Mechanic for 15yrs :D

But I completely agree, if I did it... I'm almost certain that it would've been on right, I'm very careful with gaskets like that. BUT what can you do, completely honest mistake and quickly fixed, just sucks it took that long to find something so simple.


The closest autoparts store if I would've drove there would've been 3+ hours of driving to get too, one problem when you're out in the middle of no where on the farm working. Generally we have the tools to do damn near everything, but something special like this you're sortof SOL unless a neighbor happens to have one

Starglow
03-25-2012, 01:03 PM
I'm glad to hear you found the problem....usually it's the simple stuff that kicks your butt, but don't beat yourself up too bad because everyone who works on cars has been there at one time or another if you can get them to admit it. :D