Ford EFI - fuel smell / hard to re-start

[pcf_mark]

I have all '92 Ford OEM parts in my EFI system I just control it with MegaSquirt. I have two issue both I think are related.

After driving and shutting the truck off I get a distinct fuel smell. It seems to be more toward the rear of the vehicle but it is pretty strong for a while afterward and I have no fuel leaks. I checked the fuel pressure and once the engine stops it drops to zero pretty quickly. I have a newer pump with the check valve. I had assumed it was a leaking fuel pressure regulator. However when I go to re-start it the engine is very difficult to restart. Stutters, stalls, rough, smells rich for maybe 20 seconds and if I try to rev it up sometimes to will clear up but usually I just wait for it to smooth out on its own.

I am now wondering if I have one or more leaking injectors dumping the fuel into the engine when I shut it off? Any way to test for this?

I have also some luck by turning the key on / wait 10 seconds / key off / key on wait 10 seconds to let the fuel pump run. I think when the fuel pressure drops there is very little fuel in the rail to start the engine causing EFI to be pretty confused. If I do that a few times when it is hot generally it will re-start ok.


Thanks for any good ideas you can share.
Mark

 

[bigmuddy]

Have you checked fuel pressure after the truck sits for a bit? You can buy a fairly cheap fuel gauge that screws to the schrader valve on the fuel rail. Obviously you can by a fuel pressure tool to check it as well. If its running down then I would think its either a leaky injector or a bad fuel regulator IMO/

 

[73azbronco]

Ditto, do a pressure leak down on your fuel rail. My guess on your symptoms, leaking injectors. You smell it out the exhaust pipe. How old are injectors?

 

[pcf_mark]

I can watch the fuel pressure drop as soon as the engine is shut off with a pressure gage on the shrader valve on the rail. I also think once the rail pressure drops the fuel boils from engine heat adding to the hard start issues. Injectors are 30 years old. Can I just pull then out and test them or the regulator?

 

[Broncobowsher]

Clamp off the return line and see if that holds pressure at key off. Do the same for the supply (just because the fuel pump has a check valve dosen't mean it is working. If it still bleeds off pressure the only thing left is a leaky injector(s).

 

[lars]

Pinch the return line with your favorite tool- vise grips, c-clamp etc. Turn key to run for a couple of cycles so fuel pump runs and builds pressure. If it doesn’t bleed down then the problem is the FPR. Otherwise it’s the pump or an injector.

 

[lars]

Bowsher beat me to it. Direct measurement.

 

[ba123]

Sure you have the regulator in the right spot in the system? If it’s on the fuel rail, then obviously, but otherwise could make a difference.

Just thinking maybe you put it before and it’s supposed to be after…just a thought.

 

[bigmuddy]

Pinch the return line with your favorite tool- vise grips, c-clamp etc. Turn key to run for a couple of cycles so fuel pump runs and builds pressure. If it doesn’t bleed down then the problem is the FPR. Otherwise it’s the pump or an injector.

Broncobowsher/Lars, dang you forget stuff when you have worked on an engine in awhile. Storing this away again in the old brain files..

 

[pcf_mark]

Can I safely pinch the plastic oem line?

 

[73azbronco]

Is it original? No, to old. OK wait, you have oem nylon fuel line, is that under EFI pressure? That stuff was only made for suction really, to a carb, or engine mounted fuel pump.

 

[ba123]

or maybe he means the efi stock nylon line, but I wouldn't pinch either one. It's not made to be pinched like a rubber hose.

 

[pcf_mark]

Late model Ford EFI nylon lines in both directions with OEM fittings. I do not see a way to pinch it maybe I can rig something temporarily.

 

[Speedrdr]

If it was something that I was going to do, I’d cut the line into and put an inline cut off there. That not only avoids the ‘pinching the one’ but gives a convenient fuel shutoff.

Randy