hard starting

[mallet2442]

Help? If I let my 84 6.2NA set a day with out cranking it is hard to start, and the longer it set's the harder it is to start. Now it dosent like starting in the cold mornings. I was thinking it was the lift pump but now it mite be the glow plugs? I need to fex this asap, Im going up north to hunt and dont want to wast good hunting time working on truck.

[catmandoo]

the longer it sets the harder it starts sounds like fuel bleeding off

[britannic]

When it does start, how does it run for the first few minutes? Any smoke, surging, stalling, hesitation etc.?

[mallet2442]

It turns over a cuple of times and then cranks and runs for for a few secunds then shuts off. Then when you turn it over it hits sparaticly for a many turns the it cranks and runs for only a few secunds again. The longer it set's the more this happens befor it well crank and run.

[aloharovers]

Sounds like air in the fuel lines.
I installed a clear piece of tube from the injector pump to the steel return line. Then look for bubbles in this line just after starting the truck.
Pete

[Kadzban]

A buddies 86 K30 6.2L had a leak in the line from the tank to the lift pump cause a similar problem.

[britannic]

Under vacuum (such as when the fuel contracts in the tank and lines due to cooling overnight etc) air can be drawn into the fuel system through air only leaks, even when there aren't any apparent fuel leaks.

Another cause, is when the mechanical lift pump doesn't have a check valve or that valve fails, allowing vacuum from the tank to release dissolved air in the fuel between the lift pump and the IP. When the engine is cranked, the IP transfer pump gulps air until the lift pump comes up to pressure and vents it through the the IPs vent wire back to the tank via the return line. Meantime the IP stops injecting fuel and the engine stalls, or surges until the lift pump gets the pressure up above 5-7psi.

[mallet2442]

Thanks for your input! I have an electric lift pump to put on it. Ill check for the leeks while Im installing the lift pump. Could any body tell me where and how the electric pump should be wired?

[britannic]

It could be wired using a relay that initially is activated by the glow circuit feed to the wait light or some other ignition switch related circuit, to briefly pressurize the system and then shutoff the pump. A feed from the oil pressure switch would take over once the engine is cranked/running.

An inhibitor switch activated by impact, that can be reset afterward, would be a good idea to prevent fuel being pumped out of ruptured lines after a collision.

The circuitry/harnesses/switches/relays may be available from a scrapped 6.5LTD, which uses a similar set up.

[mallet2442]

Starting not a problem any more! I totaled the truck last week going home. I was hit in the rear by a 79 mustang and it nocked my rear end around, I slid side ways across four lans of trafic hit the gard rail rite in front of the lift rear tire flipped over two and half time landing on the roof. When I opened my eys I realized the motor was still runing,I was hanging upside down in my seatbelt and woured about getting out. I looked around and saw that geting out wasent a problem becouse all the glass was gone. I turend the engine off unhucked the seatbealt and crawled out. The only thing left in the truck was me and me coumputer bage. Everthing else was on the ditch bank, even my cell phone witch was on my side when I got hit. I walked away with some bruses and a copul of cuts. If I had been in my other car (85 subaru brat) I dont think I would of made it.Im more convinced about the suburban and Im looking for another one. Oh ya the mustang that coused the problem had a dent in the lift front qourter panel, he drove home. That is after he got a ticket for reckless driving. And Im still whating for there insurence to get back to me. What do you think? Would the engine and runnung gear be wourth much. Its a 84 6.2 700r 4x4 with 175K miles and the motor did run for a few minutes upside down?

[ropinfool]

Sounds like someones keeping an eye on you. You got really lucky. Glad to hear you're ok. John

[gavio]

I sure hope your next truck is easier to start 'cuz I'd hate to see you go through THAT again :D

Glad you're OK - good luck.

[Dieselboy]

Glad you're okay.