Engine/Transmission (1994 - 1998) '96 12 valve with a hard start ??

[JPLB22]

My friend and boss is the owner of a '96 12 valve, automatic, that has a hard start. I don't know alot about the 12 valvers, I've owned an '02 and an '03. So I was hoping you guys could give us some help.



The hard start on his truck happens the same whether the engine is started cold or hot, temp makes no difference. It will turn over maybe 6 times or so and then fire. It always fires though. It was doing this hard start thing before and still does it after his most recent fuel filter change. But when he revs the engine up to 1800 rpm or so and kills it while at 1800 rpms, it will always fire up on the first crank next time he tries to start it.



So bottom line is, the truck always has a hard start unless he kills the engine while holding the rpms at 1800. What could be wrong ?



TIA



Jeff

 

[K5IP]

One place to look is the two rubber hoses, one supply and one return which connect the engine fuel system parts with the fuel tank parts.

When these lines age they can cause "loss of prime".

There are many posts on this issue. Take a look!

 

[Got Smoke?]

Sounds like air in the lines from cracked hoses.



Do a search on fuel return hose and you'll find plenty worth reading.



You can buy new fuel line cheap nearby usualy, but if not LarryB sell's a kit.



www.FosterTruck.com

 

[Cooker]

If I am reading this right you are saying he could shut the truck down and immediately try to restart it and it will not start well?



If so I don't think dry rotted fuel lines are the only problem.



My first guess is the FP is pretty low, quite often times from a bad overflow valve. Next to check would be the fuel shutdown solenoid circuit.



If it only happens after it sits a bit then I would agree with the others that the fuel lines are likely the culprit.

 

[Joseph Donnelly]

Or, the lift pump could be going bad and not pumping enough fuel at low rpm.

 

[ProMac1K]

Has he tampered with the pump at all?

 

[tURBOdIEZEl]

sounds like return fuel line is cracked..... does he run any additves that clean the injectors? how many miles on the truck?

 

[wcjp]

Unless the fuel supply/return lines are new I don't see how they can be ruled out. When mine had hard start issues both fuel lines and the preheater-lift pump soft line was also dryrotted. The screen and associated gaskets for the fuel preheater also needed to be replaced.



If this is a 4x4 the fuel lines are easier to access if the driveline and starter are out of the way (but not necessary). If the starter is removed it's also a great time to replace the starter contacts with LarryB's upgraded contacts.

 

[ABorchard]

If it's starting hard after being shut down for only a few minutes I would suspect it's electrical in the starting system. Bad battery(s) connections or needs new starter contacts.

 

[JPLB22]

Thanks for all the quick replies !



The truck is bone stock. It's got about 120,000 miles on it. We will definately check the supply and return lines for rot. If we rule those out, then we can check the fuel shut down solenoid circuit and the overflow valve.



Thanks again, it may be a little while before I can report back, we're pretty busy right now.



Jeff

 

[Lsfarm]

Low Idle setting

A lot of 12v's crank a few revolutions before catching, especially if the idle is set low.



See if the truck fires up quicker if you give the throttle a tap once you begin to crank the engine.



The 24v's start best with no throttle, the 12v's fire off best with a bit of throttle applied.



Let us know what you find out.



Greg L

 

[ProMac1K]

Yep, that's why I was curious if the pump had been tampered with. A low idle, or a misadjusted governor will do this.

 

[JPLB22]

Sorry it has taken so long to reply, but like I said we're pretty busy right now.



He told me 2 days ago that he found a rubber portion of the feed line that looked pretty bad on one end. So he replaced that piece of line and did the fuel filter again. So far everything is back to normal.



He told me to tell everyone thanks for their help !



Jeff

 

[BTighe]

tell him to check the site out. its only 35bucks anyway. well worth the small investment.