1985 F250 6.9 IDI cranks smokes but won't start. HELP PLEASE!!!

[Smogman]

I have seen several posts on this subject but none that i have seen are exactly the same as my issue so here goes.

I have had this truck for three years. It has a Golden Fuel Systems Veggie Oil System that was installed by a professional. Non-turbo. It has always leaked air into the system that I would purge at the filter and it would start and run fine. This spring i tried to start it for the first time and it cranked but would not run. It sputters like it has air in the system then occasionally catches for an instant and then dies like it isn't getting fuel. Bled the air out and still no joy. I replaced the starter and it ran for a day or two then again was unable to start. replaced fuel pump and it started perfectly for two days then back to the same exact symptoms. I separated the veggie oil system from the diesel to remove the possibility that the WVO system was introducing air. Fuel filter is full of diesel and no air in system. I replaced the IP with a used one from a 7.3, still no luck. I am getting fuel at the filter and to the IP. Both of the IP reacted the same way, i.e. no diesel came out at all to the injectors. Soelnoids high and low are good, glow plugs test fine. A spritz of starter fluid gave me a catch and smoke, but dies immediately. Batteries and connections are good.

I need this truck to run as it is my daily driver. It has always been tough to start but ran perfectly after air was bled.

I have been racking my brain as to what it could be, and don't want to buy an IP if I don't have to. Thanks in advance for any advice you can give that might help me get it back on the road!

 

[Kistthesky]

do you have constant 4-5psi fuel pressure at the schrader valve on the filter? sounds to me like you have a restriction somewhere in the tank or lines.

 

[Smogman]

yes, good pressure and steady flow of fuel. Was thinking of bypassing the separator/filter but it didn't seem to be the issue.

 

[TahoeTom]

Maybe some of the old WVO has gelled and is still present, restricting the IP. I seem to recall a member with similar issues got his started after warming the IP with a heat gun or hair dryer. You could fill the fuel filter with ATF and try and get it through the system. Do you have a mechanical fuel pump? I run a mechanical pump but bleeding air with them is a PITA and ******* starters. Many here use the Carrier Transcold electric fuel pumps. Another thing you could try is to run off a small fuel can to eliminate the plumbing back to the tanks.

 

[Smogman]

Have not used the WVO system since I bought it. Need to blow out the lines and replace the filters and get my filtration system set up first, so it has only had diesel fuel through it. I am using a brand new mechanical pump. I see a lot of mention of a lift pump, that is the fuel pump, right? This is confounding me and I still think it is an air leak as it ran good for a couple of days and then I parked it on the slightest of inclines and it would not start. thanks for your input.

 

[TahoeTom]

Fuel pump is the lift pump. Not to be confused with the injection pump. Replacing all your return lines is a good place to start to eliminate air intrusion. Is the original fuel water separator still hooked up? It is on the firewall next to the brake booster. These 6.9 F/W separators are known to let air in the system. You can bypass it to eliminate that as a possibility.

 

[laserjock]

If you have fuel to the pump and no fuel at the injectors and it does it with both pumps, try jumping your fuel shutoff to battery to make sure its working. Maybe you have a bad wire that is causing an intermittent problem.

 

[Smogman]

That was my next move, to replace the return lines and o-rings, tees, etc. I will have to check but am fairly certain that the original separator is still in use. thanks for the advice guys.

 

[franklin2]

If you have smoke coming out of the tailpipe, then you have fuel. I would do a compression check since the ether didn't make it go.

 

[idi_Marty]

+1 on what laserjock said, I would check to make certain that the fuel shutoff isn't your problem. If you changed ip and still no fuel, maybe your fuel shutoff wire has gone bad.