Engine/Transmission (1994 - 1998) Engine starts fine, runs for 30 seconds then dies. Hard to restart.

[Extreme1]

This started happening about 3 weeks ago and it just got above freezing a few days ago during the day. If it's below freezing , the engine starts fine, runs for about 30 seconds and dies. If it's above freezing, the engine starts and runs normally. 23 degrees is the closest I've gotten to 32 from the low side and yesterday it started and ran fine at 34 degrees.



When it starts to die, it drops a couple cylinders and things go downhill from there. One seems to keep trying to fire but it isn't enough to keep it going. Then I have to crank the engine a lot in order to get it started.



If I start the engine and rev it to 1,200 RPM, it will try to die but work it's way through the problem and then run like normal. There isn't any smoke when it stays running but is trying to die.



I thought this was either water in the fuel system or a bad return line. I drained the fuel filter and then checked the return line hose clamps. The 3 year old hose was damp and the top clamp was a little loose so I cranked it tight but it still does it.



My next step will be to replace the filter and the hoses. Does this sound familiar? I thought bad hoses made the engine start hard from the git-go, not start then die. (Sorry for the novel).

 

[woodsrat]

extreme 1

had a 90 in the shop doing the same thing but it was not due to the weather. had a bad gasket on top of the fuel filter housing, thought we had it fixed ran about 15min then started doing it again there was a crack in the suction line right at the frame rail on top of the tank factory metal lines.

 

[HoleshotHolset]

You're getting air in the system somewhere.



Mine did something similar to that when I replaced my rubber lines, etc.



Matt

 

[DMC]

I'm betting your overflow valve is bad too. I had a hard start problem like yours. I would pump the primer on the lift pump and it would crank up fine as long as it didn't sit to long. While I was looking around after I changed the lift pump I noticed slight dampness at the return hose. Tightened it up, a couple of months later I had a leak at the return line. Changed both lines all has been good, cranks good all the time now.



I think what happens is your overflow valve gets weak and you don't really notice it until the return line starts going bad. With a bad overflow valve it will get a little air in the pump.



At least thats my story



Don

 

[Joe G.]

The variation in temperature that affects it make me think you ought to check to see if your fuel heater is working. It's the black plastic disk just above the pre-filter screen in that assembly. There is a cable going to it. Two of the wires go to a temp sensor that is attached to the top of the heater/pre-filter assembly. The other wires are in a connector that plugs into the black plastic disk. It's easy to take out. Remove the pre-filter housing that has the screen in it. Then an allen wrench will remove the fuel heater, 8mm I think. The temp sensor is a PITA to get at. It takes a small torx bit to remove. I don't know what size.

 

[Extreme1]

Healed!

Last night I finally had time (and no rain/snow) to work on the problem. I was pretty sure it was air in the fuel and was due for a filter change anyway so I bought some hose and went to it.



The first one I pulled off that goes from the tank line to the heater had a rubbed spot on the back. It appears that the heat/noise barrier against the firewall is loose and rubbed a hole in the backside of the hose. The temperature fluxuation must have been enough to open and close the hole enough to allow it to loose prime but there was still enough fuel in the heater and filter to start and run briefly.



It's nice to have the truck be dependable again!

 

[DMC]

Glad you were able to fix it. It feels good to remedy problems yourself. And keep strangers out from under your hood.



Have a good one



Don