Greetings All
My '88 is demonstrating the Hard starting problem that I have read so much about here that I am now ready to start working on correcting problems in the fuel supply system. This will be much more than a couple pieces of fuel line. Somewhere in the chain of previous owners the wiring harness has been hacked into around the tanks for various reasons and it looks to me like the interconnects between the injectors and the IP to the fuel filter are all still factory, they are the braided fabric covered lines.
SO...... here are some questions:
1) Can I buy a factory wiring harness that would run back to the tank selector switch, tanks and rear lights and bumper for an '88, if so where?

2) Should I replace the fabric covered interconnects between the injectors, or are they considered to be life of the vehicle parts?

3) I am planning to replace the factory fuel filter with a Racor. The factory setup has what looks like a bypass that runs from the IP to the filter mount. Any suggestions about where to route this would be appreciated.

4) I have read that the return lines to the tanks need work but I'm not clear as to what the fix is or the symptom that I should be looking for to fix.

Lots of questions, but I have a window of time that I would like to fill with correcting these problems.

Thanks in advance.

Ron

 

Ok, Change the fuel lines that go between each injector, any diesel rated hose will work. As for return lines, take the old ones off and replace them with new hose, rubber is fine, make sure its diesel rated etc. with todays use of bio fuels you don't want the methanol found in biodiesel eating your rubber.....trust me its no fun. Also you might want to change the injector O rings, I just changed mine about a month ago and if your truck is all original they will need it. All mine were hard and cracked. I'm not sure on the fuel filter situation, I have a 6.9 so I think its different but I'm sure someone will let you know. You can never go wrong with putting new fuel lines on, especially if you dont know the history of the truck.

 

Thanks Basspro, pretty much confirms my "Gut" feeling.

I did mis-state one thing though. The bypass comes from the #1 injector to the fuel filter. The same bank, passenger side has a bypass at the rear near the firewall. So with the new filter I'm wondering if I could route the forward bypass back to the rest of the bypass system?

Basically, I think where I'm headed is that if it carries fuel, I'm replacing it unless its made of steel.

 

I was told to get rid of that bypass....I just put a piece of rubber hose on the filter housing and then plugged it with a piece of metal I cut from a drill chuck and then clamped it. You have the right mentality about replacing it if it is carries fuel. If you want to spend the extra cash, you can get braided steel hose that you will never need to replace but I think thats a little much. If I had the money I would do it but Im a poor college kid so yah not happening.

 

Just pulled the interconnect and bypass fuel lines off, I can't believe that this truck even ran.
Leaves me wondering what else I'm going to find.

Ron

 

That bypass hose is a good thing. It bleeds off air in the filter so it doesn't go to the IP. It will run without it, but like I said its a good thing not bad.

Braided stainless lines don't really last much longer as they are still rubber hoses that deteriorate. They sure are pretty though.

 

OK, there's something that I didn't know. So, when others have converted to a Racor filter setup is there a way to preserve the bleed line?

Thanks

Ron

 

Uh ... (nervous chuckle) ... does this mean if I walk up to the parts counter at Knechts and ask for three feet of 1/4" fuel line, they might be giving me something that melts when exposed to diesel? I assumed fuel line was OK for either fuel ... should I get all worried now and go replace all the injector return lines I just swapped out?

(BTW it runs great now, no more fuel drainback!)

--Finn John (90 F250 XLT/L std cab 5spd 4x4, 4.10s)
Corvallis/Albany, Ore.

 

"Fuel rated" fule line will work fine. .. You want that fuel return bypass line on your motor. Like stated before, that line bleeds air into the return system and not through the pump and it also dumps excess fuel pressure. You can have to much housing pressure on one of these pumps.

 

OK, so when I change over to the Racor filter can I just route the various return lines all to the back and down the return line? The bypass that comes off of the #1 cylinder, as stock, goes to the factory filter mount. Does this create a small "Plull" to help draw the air and fuel through the system? If so, any suggestions how to create this with the Racor mount?

Thanks

 

Getting rid of the fuel bypass at the filter is not such a good thing actually, one of the diesel techs here explained it to me once.

The bypass can actually help to purge air from the filter that can collect, and most systems will collect some amount of air even if working perfectly. This also makes startup much easier after a filter change.

I recently reinstalled my bypass with a clear tubing, and you might be suprised at how much fuel normally flows through it. The same guy said that if you block off that fuel bypass, you will throw of the pressure of the IP, and put more fuel pressure in the IP housing than it was intended for.

If air is getting in your system, then you have an air leak somewhere, and blocking off the bypass is more of a bandaid fix. There is supposed to me a check valve at the line to prevent drainback to the tank, and if its not working, it could cause a drainback condition.

 

The idea of the bypass makes complete sense, I get that. But this is the first that I have heard of a check valve to stop drainback, and my truck doesn't have one. Makes the hard sarting symptom start to make even more sense.

So where abouts would I go about finding a check valve?

Thanks David.

 

Ford ussued a TSB on the drainback problem back in the early 90s, I think a ford or navistar dealer should be able to get one for you. An autoparts store may also have a more generic one that could be made to work, since a check valve is a fairly comon device on fuel systems.

The check valve on mine is located at the filter head, but I have a 7.3 style filter. The check valve is integrated into the fitting for the fuel line, and you wouldn't know its actually also a check valve, unless you were to take the fitting off and examine it more closely.

The injector pump also apears to have one at the fuel return line on top of the IP. It ""looks"" like an adapter for the brass elbow that conects the IP to the return line that runs to the back of the engine.

 

Hmmm, good points. I also have the 7.3 but I don't know if the filter bracket is the stock fitment or not. I will pull it and look closer.

Thanks David

 

OK, so now I've pulled the fuel filter bracket and it is deffinatley an International part, and now I know that one of the P.O.'s tricks was to hide unused wires wrapped back on the harness. I guess I need to find information about the correct setup, which wires do what and what the connectors are supposed to look like. I might just buy a Racor and abandon the factory bracket. At least then I would have schematics.