Charlie

Just completed rebuilding engine. Have not driven car yet, but have cranked engine 4 or 5 times and it ran great. Last weekend I took the battery out to do a repair where the battery is. Today I put the battery in, cranked the car and it would not start. Finally got it to start but it would only run at 3000 rpm or higher and ran rough, it had a couple of small backfires during this time. If you let off the gas it would go dead. Something has changed or gone bad, any ideas what the problem might be.
I checked vacuum hoses, did not see any problem there.

Chris_924s

Check grounds??!!

Red 944

hear any vacuum leaks? under the intake manifold has some tricky bits

Charlie

I have checked grounds and hoses, don't see any problems. It ran really good last week. I feel like something has gone bad. The fuel pump must be working OK if it will run at 3000 rpms. I tested the fuel pressure at the fuel rail and it was around 35 to 40 psi during cranking and did not leak down after trying to crank. The car is very hard to start. In order to get it running I have to press the gas pedal while trying to crank.

Legoland951

If the only thing you did was to remove the battery, you want to check the positive terminal where all the other smaller wires join the battery terminal. Sometimes they come loose and not have good contact and it will cause problems. Also, the short ground bolted to the firewall about 6 inches from the negative terminal will cause this if not bolted back in.

Charlie

Will check these tomorrow and see if this is the problem.

Charlie

OK, checked terminals and they are OK. I wonder if an injector is not working properly or the DME or the AFM?

mossy

Maybe FPRs??
Are the plugs black???
Sounds like it happened all at once, I'd check that everything has been reconnected properly, then check for failed components.
Good luck.

Charlie

Pulled the injectors and tried to crank with them squirting into bottles. They all work and squirt about the same amount of fuel. I can't be sure if it is the correct amount but they are consistent. Testing a little more, I've found that the only way it will crank is if you push the pedal down and crank. It will not crank if you don't push the pedal. Could be to much fuel, not sure. I can look at plugs and report back.

Chris_924s

Hmmm.. and Patti says.... Fuel Pressure regulator.

TRUST me- she's good. Mine did the exact same thing after I swapped out the fuel rail and didnt change the FPR- it was indeed bad and caused the same problem.


fwiw-did you put in fuel recently? There has been instances of bad gasoline around here and creating all sorts of car problems lately.

Predator

When you first removed the battery, which terminal was removed first? If it was the positive terminal, you may have "sparked" it during removal, and I've heard that can screw up the ECM. Hope thats not the case, but if it is, its an $$$ fix.

Charlie

I don't know how long the gas has been in the car, since I bought it and it was not running. It smelled OK but could be bad. I had mixed some fresh in with the old, but figured since it ran so good the first 3 or 4 times I cranked it the gas was good. Might need to drain the tank.

Chris, if you think it might be the FPR, I will order a new one tomorrow and try that. I don't beleive they are very expensive.

Predator, I don't remember which terminal I unhooked first, but I suppose it could be the DME. I don't have another to test with, might have to buy a used one to test with.

Chris_924s

old gas is bad gas.. run it out as soon as you can. then get some techron and fill the tank up with fresh premium fuel. dump the techron in first then filler up immediately so it mixes well. That should clean out a lot of deposits, varnish and gunk built up from sitting. Mine sat for 3 years stored prior to it's current daily driver status.

sounds exactly like what happend to me bad FPR. Started fine, ran until warm then wouldnt start. Also had a bad (studder) over 3K rpm.. It seemed like it wasnt getting enough fuel.

Battery cables.. Negative first off. always. and last one on.
The positive will short out to the windshield frame if removed first- this sucks a lot.


Good luck- keep us posted.

SidViscous

Coil too. Chris you shyould know this.

Butvisual inspection of grounds is useless.

Do all the above and add coil.

Chris, I need to do an oil cooler now.

SidViscous

PS

Let us know what year and turbo or not, makes a difference.