Engine/Transmission (1994 - 1998) Very Hard Starting, Bad Injection Pump?

[XJin]

I have been dealing with this problem for a while. Where is a brief history of what happened so far.



Truck became hard to start gradually. It got to the point now it takes 30 to 40 seconds of cranking before it would catch. I thought it was air in the system. I junk the factory slow pressure pump system. I put in a FASS pump with JIC fittings so that I know there is no air getting into the system. I got a Drawstraw from Vulcan that has a JIC fitting coming out of it. It is simple from tank to Fass to the injection pump. I am getting 30 psi pressure at the inlet of the injection pump.



The problem is still here. I make a little test gauge to use air to test each section of the return line. It is holding pressure everywhere except for: the overflow valve that goes into the pump. The pressure in the line goes from 20 psi to 0 in about 30 seconds. I put some soapy water around the banjo bolts and I don't see any bubbles. Here are my questions:



When I pressurize the overflow valve from the return size, does the air go into the pump? Is the pump suppose to be air tight? I am getting 30 psi at the inlet of the injection pump, that is all that matter, right? Is my injection pump going bad?



I know there are a lot of brain and knowledge here. I thank in advance for anything you can share.



Xin

 

[hsmith]

Don't know the answer here, but just wanted to say my fuel pressure drops to zero in a matter of seconds when I turn off the key. Oh, and I have no problems, starting or performance.

 

[GAmes]

When it does start does it run smooth or buck and miss for awhile. When my OFV quit it was the buck and miss mode. Also, what percentage of veggie oil are you using? I have no experience with fuel other than diesel, but I'm thinking that may be a clue.

 

[mfburns]

Sounds like air in the line. THere are several posts here about this subject. If you can pressurize the tank a few pounds and look for leak. Hoses may be cracked letting air into the line, not leaking fuel out. Do a search on this and look at the suggestions there. I had a similar problem and had to replace the line. Problem solved.

 

[Missouri Mule]

Could be the fuel heater leaking air usuallly at the connector but can leak else where on the fuel heater.