cold start - starving for fuel

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Apr 6, 2004 | 01:44 PM

troyp

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cold start - starving for fuel

i have an 86 BII 2.9 4x4 stick plow truck. the only way to get it fired up cold is to squirt gas into the intake. it will fire up when you first hit the key, then quits and won't start. after it runs for about a minute, it will run perfect. it can sit for several hours and still start just fine. stone cold - fumbles once and then will not start. i have checked the fuel pressure - 40 pounds with the key on - even when it stalls on a cold start it never drops - about 30 lbs at idle and it will jump to 40 when goosed. i have a hunch the fuel lines may be soft and allowing air in there - is this possible? once it clears the lines, it will run absolutely perfect. i have not pulled the codes yet - it is a plow truck and there has been some "hacking" under the hood before i got it and i don't doubt it has set every code imaginable - however, it runs great besides the cold startup problem. any help would be appreciated.
tp

Apr 6, 2004 | 04:14 PM

mrshorty

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From: UT

Can you hear the fuel injectors firing when it won't start?

Apr 7, 2004 | 07:09 AM

troyp

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that would be strange if the injectors would fire right off the bat, quit firing for a while and then start firing again. every time. and never quit firing after the first minute or 2. however, the answer is i have never tried to listen to them while cranking it over. should you be able to hear them without a stethoscope (sp)?
i figure i should jumper the fuel pumps and clear the lines and then try to fire it up cold to eliminate the "air in the lines" theory. i will do a search on this site for exactly how to jumper them and try it out tonite.
thanks
tp

Apr 7, 2004 | 10:36 AM

mrshorty

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From: UT

Ford's fuel injectors are usually loud enough to hear without a stethoscope.
As for jumpering the fuel pumps, one of the leads to the self-test connector grounds the fuel pump relay.

Apr 7, 2004 | 03:38 PM

troyp

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anybody help with which pin to ground? i've seen the sig rtn and sto pins, but have yet to pick the fuel pump relay bypass one (only 4 other pins on that connector?)

Apr 8, 2004 | 08:54 AM

troyp

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let it sit for 12 hours, shorted the fuel pump relay bypass and ran the pumps to clear the lines - tried it and it started better but still fumbled and gasped for a little while. a definite improvement but not perfect. could the fuel filter be restricted and yet still show 40 lbs on the injector rail?
also, tried it this morning (about -7 celcius last nite) and it fired and stalled. cranked about 5 seconds and then stumbled to life - fumbled for a while and then started to run fine. definitely better than in the cold of winter. maybe it is just not compensating for the cold (adding enough fuel). from what i have read, the sensor that supplies the computer with the temperature for startup will normally fail such that it thinks its 50 below and run full rich and attempt to flood itself. could it fail the other way? any way to check that?
i'm thinking out loud here...

Apr 8, 2004 | 02:32 PM

Ken00

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From: South Jersey

The pressure running seems a little low to me, I would expect 35psi, do you have good pressure when cranking. It is possible to have good pressure KOEO and still have low flow (volume) but you should see a decrease in pressure when the demand for fuel goes up.