fuel supply/ starting issues...long

[hjalbert]

I recently replaced the injector return lines with a kit on my 1985 6.9 N/A. all new orings, caps, and copper washers under the injectors. It does not seem like they (the plastic pieces) are seating properly. Now the truck will only start easily if its been running. and a couple of times it has acted like it ran out of gas while driving. It died and left me on the side of the road, everything warmed up but it would not start. EVen After I bleed the air out by cracking the injector lines, and cranking it over it still sometimes will not start, only white smoke from the exhaust. I have replaced every soft fuel line( I run on WVO) and double hose clamped, and I looked at the inlet on the IP and that rubber seal is falling apart and hard, So I will replace it. I am going to buy new glow plugs tommorow, because I know it needs them anyway, and want to rule them out. I have an electric walbro pump mounted after the filter, which is only used for diesel, and I also installed a small facet pump on the return line which I thought would halp to solve this problem by priming the system, I only use it before "trying to start" and only until I hear fuel flow through it. Any other suggestions of what to check? I heard mention of a check valve, but do nto know if there is one on my truck, any ideas? thanks!
PS it is about 80 degrees lately, So I really do not think glow plugs are the answer.

 

[Full Monte]

You haven't said anything about if you start up on straight #2 diesel or biodiesel and heat the wvo up to temp before you switch to wvo. You also haven't said anything about switching back to #2 or bio for awhile before you shut it off. If you are just running wvo, it will harden up in the injector pump/lines when the engine is turned off and you won't get it started. Maybe you know all this already, but you didn't say. If it were my rig, I'd start by switching to #2 fuel until I solved the start/run problems. That would tell you if it's wvo related or mechanical. Have you checked your filters to insure they aren't plugged? How long have you been running wvo? Hope this helps.

 

[Full Monte]

One more thing...what's this pump on the return line for? It makes no sense to me. Are you pumping against the flow of oil returning to the tank? I never heard of anyone using a pump on a return line before.

 

[hjalbert]

Yeah, I guess I assume the obvious. to describe my sytem, heated 100gal tank, heated davco filter, HIH supply and return lines, disabled facotry lift pump. VO runs to a flat plate heat exchanger, then to the three way valve, then to the walbro pump, then to the IP, through injectors, through the pump on the return line, then to the return three way valve. The Diesel runs from either front or rear tank, through stock 6 port valve, then to the stock diesel filter, then through the 3 way valve, then through the walbro fuel pump (which puts the stock diesel filter under vacuum). then to the ip etc. I installed the pump on the return line based on some experience I have had with primjing fuel systems on some vehicles I have worked on. Often times the easiest way for me to prime the system, and the cleanest way was to suck fuel through the system using the return line as a hook up. rather then try and push through. IN this case I know if I have fuel flowing through the system comletely because the pump gets quiet when fuel reaches it. I only run this while bleeding the system, or If Is suspect there is air in there. not while the truck is running.

I start on diesel, and shut down on diesel, and I have new filters on both sides. I may have fixed the problem temporarily. I put three Orings, smallest in the front, on the inlet hose to the IP, and then tightened it down, this morning it cranked right up. We will see thanks!

 

[hjalbert]

no go, 2 hours later it was full of air again. Must have been a fluke. I need to take a long hard look at every fitting. Is there any reason I cannot replace the fuel filter inlet fitting with a regular barb? for that matter why not the supply and return on the IP? thanks

 

[hjalbert]

This is beginning to perplex me. Yesterday morning it started right up. this morning it started right up, turned it off, it started fine again and again. When driving around, it is warmed up, After I turn it off, I can start it again with ease right away, but If I wait 30 minutes plus, it takes a long time. But then when it sits over night it starts fine, on the first or second crank. I am confused!

 

[Full Monte]

Have you bypassed the stock water separator on the driver side firewall?
I'm wondering if that vacuum pump can suck in air through that unit. Just one idea.

 

[Full Monte]

This is beginning to perplex me. Yesterday morning it started right up. this morning it started right up, turned it off, it started fine again and again. When driving around, it is warmed up, After I turn it off, I can start it again with ease right away, but If I wait 30 minutes plus, it takes a long time. But then when it sits over night it starts fine, on the first or second crank. I am confused!

There's a fuel-related solenoid (can't remember the guldurn name) under the front of the injector pump. Possible problem with it?

 

[Agnem]

You mentioned your return caps not seating. Well, they need to be seated! If installed properly, the top of the return line cap doesn't touch the fuel line nut.

 

[hjalbert]

The fuel shut off solenoid is clicking, But I will have to take it out to make sure it is opening fully. I no longer have the water seperator on the firewall, it Was gone when I bought the truck, so that can not be the cause. I am in the process of changing the inlet and outlet seals on the IP and the filter, and the junction on the return. I am going to also make sure the returns are properly sealed. thanks for the advice!

 

[Exekiel69]

How many miles do you have on that Injection pump?

 

[hjalbert]

not enough, I am not ready for it to die yet