Fuel Pump...HELP!!!

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Aug 26, 2011 | 11:29 PM

xxstroker_acexx

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Joined: Aug 2011

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From: In the Georgia clay

Fuel Pump...HELP!!!

My 1986 Bronco II w/ a 4.0L conversion is being acting up to say the least and I'm at a loss. When it's hot outside (been 98 here the past week) and the Bronco starts missing very badly and will eventually die. After it died the other day I popped the hood and messed with the pressure release valve on the fuel rail and there wasnt much gas coming out at all, it was a mist of gas with quite a bit of air, making me think that the secondary fuel pump (under the driver side on the rail) is getting hot and not functioning properly. It doesnt do it when the air temp outside is cool or when u first start it, only after it gets to normal operating temps and its hot outside. Now then big question what is the problem, has anyone else experienced this, and what can I do.

Aug 27, 2011 | 10:07 AM

DFWBII

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Joined: Jan 2011

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From: Arlington,Texas

Quote:

Originally Posted by xxstroker_acexx

stroker_ace,, hmmm,,I had the same problem last Sunday with my BII, 2.9FI,, as it was hot day-107 and I had been setting in traffic, going up/down hills. Mine just sputtered and died on I-30 going toward FtWorth. pulled off road and temp. gage was just into the DANGER(Hot) Zone,, had plenty of gas. let it cool a bit, like 5 minutes and it started right up. Evidently the gas in the reg./fuel rail/and injectors was boiling(vapor lock) from intense abnormal heat. Got home and the fan was making terrible racket and loose. I installed new clutch/fan and flushed system and re-filled with fresh anti-freeze,,50/50,,that helped the cooling a lot. hasn't died or got hot since,,, stays in Normal area. hope you getter fixed,,,

Larry.

Aug 27, 2011 | 10:40 PM

mrshorty

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Joined: Dec 2001

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From: UT

Quote:

Now then big question what is the problem, has anyone else experienced this,

I had a similar problem on my Explorer. On hot summer days, the fuel pump would overheat and stop pumping right. Other than the fact that your high pressure pump is external, you would have the same basic fuel system design. Diagnosing it was pretty easy -- put a fuel pressure gauge on it when it was acting up, and it was obvious that the fuel pressure was too low. If I were in your shoes, I'd get a fuel pressure gauge and see what it is doing when it is acting up. Once I had determined that it was the pump (and not a relay or other something acting up when hot) I replaced the fuel pump and haven't had a problem.