1996 Chevy 6.5L Turbo hard start

[jeff6.5]

Hey all:
I picked up a 1996 Chevrolet 6.5L turbocharged plow truck (not roadworthy), and it's difficult to start. There is a fuel leak immediately following the priming. I think it's coming from the hose or fuel line between the fuel filter housing and the lift pump. Does this sound familiar to anyone??? If so, is it a pain to replace the hose or fuel line? I'm trying to get a feel for what I'm getting into before I put a mattress on top of the engine to work on this thing! Thanks, Jeff

 

[Will L.]

Welcome.
Yes a fuel leak - or points where air gets into the fuel line will cause hard starting, no starting, running rough, loss of power & mpg, etc.

Just patching together or looking for upgrades where available is a primary question.

Your fuel line (factory anyways) is 3/8” from tank through LP (Lift Pump) up to the FFM (Fuel Filter Manager). From the FFM to the ip (injection pump) it is 5/16”. Then there is a return line that comes out of the front of the ip about 6” long that sits in an upside down U shape. That is 1/4”.

Many people do a FTB (Feed The Beast) modification where the fittings and hose thats 5/16 gets enlarged to 3/8”. Never heard of anyone ever that did it and said they regret it, not critical.
All the rubber fuel line should be replaced by age and because the diesel fuel nowadays has ethanol/ methanol in it and it erodes the rubber line from the inside out and can plug up or even damage the ip or injectors. So buy SAE30R9 fuel line, and get quality new clamps at same time.

A STRONG suggestion- the 1/4” line should be permanent replaced with clear tubing. The proper stuff is available from Fuel-line.com and is rated for the fuel, just not rated for abrasions- but where this tiny piece is makes it not an issue. Or from hardware stores you can get the clear pvc tubing. But it lasts 3-5 years before needing replacement.
The clear tubing shows you whenever the LP is running & key on that you have no contaminants and no air bubbles flowing. If his is step 1 of engine diagnostics from GM. So everyone learns to just leave the clear in place permanently.

The other upgrade I push really hard for is a fuel pressure gauge mounted innthe dash. Buy a metal T fitting that attaches directly to the ip and has no rubber hose afterwards. The T fitting would add a 1/8” female so you can screw the gauge sending unit into it. You should have the ds4 ip which is electronic- no cable from pedal to ip, only wiring. The ds4 ip should have 8-14psi. It will run with less than 8 but performance suffers. Under 1 psi or into a vacuum- it does major damage to the ip very quickly. Brand new ip gets ruined in under 10,000 miles. So the gauge becomes insurance to save the ip life. Not critical now, but do asap.

after replacing fuel lines it is hard to start- remember you can cycle the key many times to charge the fuel lines.

I do not suggest installing a new filter at the same time. Get the lines on, get engine to start and run. Then you can do the fuel filter- others may disagree.

Oh, new LP if needed. The best version of the factory LP is an AC Delco EP158. Tons of testing of the different part numbers, brands, etc has been done. Why they still suck: barely 8-9 psi and tend to burn out before 20,000 miles. Sometimes half that. There are better and MUCH BETTER options but they are pricey. So since you just got the truck and might hate it before end of winter- maybe stay with factory for now.