Idles good, then starts surging underway.

[5akman]

I posted a week or so ago about the 1987 F250 that my 19 yr old son purchased. It would idle but not run at speed but surged and bucked like crazy. The history on the truck is that it has around 250K on it with at least two life pump replacements, injectors and IJ pump rebuild. And, its sat for around 4 yrs prior to him buying it.

I added half Diesel Kleen, half ATF to the new fuel filter, ran it for a minute or so and let it sit for a few days. We started it up yesterday and it idled great as before and, drove great - for about a mile or so. I was able to run it through the gears and up to about 60 mph with no issues. As we were congratulating ourselves on the "cheap" fix, it started surging/bucking again and then died. It took a while to get started again and then proceeded to do the surging the last 1/4 mile back to the garage. I had to keep feathering the clutch to keep it running as it surged like crazy with the clutch out.

What is the "mileage capacity" on the fuel filter? I'm wondering if we ran the mile or so off of the fuel/ATF in the filter and then when that ran out it started starving for fuel? Any thoughts?

 

[Thewespaul]

To me it sounds like your tanks are full of rust and it’s clogging your filter or pump up and you’re not getting the flow you need. Pull the filter off and cut it apart and see if it’s full of crud. Did the fuel filter light come on during the drive? Installing a fuel pressure gauge off the filter housing would help narrow it down.

 

[5akman]

No filter light while underway and I did use a pressure gauge off the shrader valve and pressure looked ok ( pressure gauge reading surged with engine cranking rhythm?), out put looked ok also.

 

[Thewespaul]

Hook it up to a line so you can monitor the pressure while driving

 

[5akman]

Good idea, will do!

 

[genscripter]

If you don't want to install an inline tee and pressure hose to the interior of the cab, you can setup a phone camera or gopro with a flashlight in the engine bay of your truck, then take it for a drive. It'll record a video of your fuel pressure, and you can get the gist of the engine performance by the sound of the RPM's.