cold start issue

Knuckledragger · Nov 19, 2019

I have had two trucks do the very same thing and have yet to figure out the solution.

After sitting at least overnight, the truck starts up right away, runs for a couple of seconds and quits. After cranking for a good long while (4 or 5 5 second cranks), it will finally restart, run rough for a moment, then settle into a good idle.

The rest of the day, no problems at all, quick starts and good running.

I am guessing that my lift pump may be going bad, perhaps a slightly damaged diaphragm. Has anyone else had this AND have you found a common solution? Thanks!

Knuckledragger · Nov 19, 2019

Cold start is a relative thing, this just means it has not run for 6-8 hours or more. Do not have to deal with frigid midwest weather here.

chillman88 · Nov 20, 2019

You have a small air leak in your fuel system somewhere. First thing to check is the return line caps on your injectors. If they're not leaking start scouring the fuel system for leaks, most likely above the lift pump but not necessarily.

Common leak points are the fuel heater, the bowl on the bottom of the fuel filter, return lines, and the hard lines where they meet the fuel filter/ip, and occasionally the advance arm seal on the injection pump itself.

Starts up right away and then dies and starts hard is a dead giveaway for air in the fuel system.

Thewespaul · Nov 20, 2019

Something that really helps with drianback issues like this is adding a diesel rated check valve into the soft line right before the lift pump. This keeps your whole fuel system around the engine primed and is much more reliable than relying on the “finger over a straw pulling water out of a glass” scenario where any little pinhole that allows air in after shutdown lets the entire system drain back and fill your fuel filter with air.
https://classicdieseldesigns.com/products/billet-3-8-check-valve?_pos=1&_sid=a7a8aae39&_ss=r

Randy Bush · Nov 20, 2019

Put the check valve in. One of mine was doing that , start and die. Put the check valve in, also I used the good full wrap hose clamps rather then normal one , does not cut into the hose that way. Got it from Wes, and solved the problem starts and runs normal now.

5min fix, start with this as long as no visual fuel leaks topside.

Jim993 · Nov 25, 2019

My '85 F 250 6.9 had that exact symptom. Replaced the rubber seals in the line between the lift pump and the injection pump- FIXED.

This was in 1998, the truck is still mine and is still fixed.

It only takes a tiny seep, which will be evidenced by a damp area.

cold start issue

Knuckledragger

blowing chunks and grabbing porcelain

Knuckledragger

blowing chunks and grabbing porcelain

chillman88

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Thewespaul

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Randy Bush

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Jim993

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