losing prime (and my mind)

[Moses]

i believe my truck is loosing prime, it happens irregularly but too often. When i shut it down it sometimes won't start back up. i pull the plugs and crank on the starter (in intervals) until i see the tell-tale white mist, then i stick my nose in the engine compartment to make sure it's fuel mist and not frying starter smoke. Pop the plugs in and it starts right up. Except this morning (and the other time) i had let it idle for 5 minutes or so, it stalled and hasn't started with method described above.

So, i am starting a fire out in the shop and spending the day on this, hope it's a one day fix.


DmaxMaverick posted 15 March, 2005:
The clear line should be installed onto the return line on the injection pump. The fuel flow is very low pressure (or should be), so a snug fit is all that is necessary. Be sure to remove the fuel cap when you do it to prevent back pressure. If you have air entering the system, it will show up there. I've found it helpful to install the line with a verticle loop in it so the air will "trap", to be seen easier. Well i've got the clear line in, but forgot about taking off the fuel cap. So i'll remove the cap and get it started and take a drive, then the air will finally exit the verticle loop, right?

also, my loop is installed on the left side return line that connects to the "T" that goes to the IP, is this incorrect? i have to get the right size tubing (bigger) if my present set up is incorrect.

and lastly, if i am losing prime how do i find where the air is getting in to my system?

thanks a ton!

[DmaxMaverick]

Short of lines/hoses with holes, there are very few places air can get in. Check your fuel filters and all connections you can find. The fuel filters or fuel lift pump (mechanical in your case) are the usual suspects. A worn out injector(s) can allow air to enter and get pulled back through the system if you have tank vacuum, by either a faulty cap or gravity, but it is not common to cause such a problem as yours (usually requires long term storage).

Your clear line should be on the hose connection that comes out of the top of the pump.

Another possibility is the input shaft on the pump (throttle cable pulls on it), but it is usually easy to find because it will leak out more fuel than the air it lets in. If you have fuel leaking from the pump area and making a mess under the pump, that is probably one source.

Stay with it and report your findings. You are at the right place to hammer it out.

[Moses]

well.....

I am slow and methodic (anal is more like it), but i replaced every fuel hose and clap in the system. It took me all weekeend because i spent the first day just getting ready and i replaced the front brake pads as well, but i figure i saved over $400 in labor costs, so the twenty hours was worth it.

I am pretty confident that i stopped the air from entering the system but can't road test it until i bleed the brakes (tonight).

I am pleased with how fimilar i am becoming with my rig, the costly lessons of buying a "needs-work" rig will pay me dividends over and over in the future. These engines are great to work on and easy to keep running, i hope anyway.


thanks everyone,
moe

[ZZ]

I had this same problem last winter (2004). My truck was a bitch to start every morning. I changed fuel filters & lift pump and checked all the connections I could find. I finally put it in the shop and they found out that the hose was cracked on the little drain valve beside the "goose neck" They cut off the end of the hose and put on a new clamp. It has started like a champ every morning since.

[ 04-19-2005, 06:45 PM: Message edited by: ZZ ]