1989 f250 5.8 runs then dies, then runs...then dies...on and on

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Dec 28, 2006 | 02:36 PM

#16

subford

Fleet Owner

Joined: Aug 2005

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From: Easton,Ks

From what you say it is foregone conclusion that it will not pass the time/volume test.

The hi pressure should run steady and it will not slow down or stop when the head rises or it loses prime as fuel will be pumped right back into the tanks as it runs.
I would put a test light on the power wire as it goes into the pump as it runs and see if it flutters or has a steady light when the pump messes up.

Last edited by subford; Dec 28, 2006 at 02:39 PM.

Jan 1, 2007 | 06:27 AM

#17

1989f250lariat

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Joined: Jan 2006

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Took the bed off

Took the bed off, connector on the rear lift pump was heavily corroded, put power to both lift pumps, neither work - verifed good power to pumps but they're dead -

Jan 6, 2007 | 10:47 AM

#18

1989f250lariat

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Problem solved

turned out that BOTH lift pumps were bad. Seems like if you let truck sit for a while, dual function resevoir would fill (siphon?) with gas and allow truck to start and run for a short time, but after about a minute, high press frame rail pump would be starved out. By doing the time / volume test at the dual function resevoir, then verifying good 12v and ground at the pump, pumps did not function. Bought // installed new pumps, runs like a champ. Too bad pumps are 160.00 a pop....

Thanks for all the input and advice from everyone while I was diagnosing this -

Feb 24, 2007 | 08:17 AM

#19

koolkat32

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Same problem here

I had the same problem with my ford....there is a M.A.P. sensor located on the upper passenger side firewall next to the AC housing unit. Dont run out and buy one before testing it first...they are 60 bucks. All you need to do to test it is with the engine running unplug the darn thing....the engine will idle a little faster and it should stop the surging. Replace if this is the case....