My friend showed me this problem he is having tonight. His LNF (08 tons of KM's) has a hard time turning over when he puts gas in.

He would put 10-15 dollars or even fill it up. turn it over and hold it downtrying to get it to turn over for a few seconds. if it didnt turn over within the first 5 seconds he woul dtry again and it would rev like a bastard.

Any ideas what this could be? ive never read or heard about this before. He did run out of gas well driving at one point, could that be a factor? anyone else have this issue? seems really odd.

Thanks

 

Cam driven high pressure fuel pump like any other cam driven pump you run it dry and you burn out the seals .. at low pressure . ( if it is really cold out ) metals tend to condense so the engine is acting like its not getting any fuel and the ecu is compensating telling the fuel pump to kick it in high gear forcing more fuel thorugh to get the pump to respond sky rocketing the RPM's in a last resort to get some fuel .. . My guess .. I mean even if you have a fuel pump thats not cam driven and you start it with ether even after the ether burns off it will rev high to keep the engine going ..

 

okay so that was his problem. thank you i apperciate the info

 

so he replaced the cdfp and it fixed it?

 

dude you're not supposed to use the one that says diesel lol

 

no not yet

 

oh the way you worded it sounded like it.

 

The mechanical high-pressure fuel pump should not die from running out of gas once. Because once it starves for fuel the vehicle will immediately shut down. I suppose it's not great for components and I wouldn't do it a lot, just like with any fuel injection system, but GM has probably tested this countless times in development and wouldn't let a car out the door that may come back for warranty because it ran out of fuel.

Just to clarify, when you say turn it down and hold it over, you're talking about the ignition key, correct? He's not trying to push down on the gas at all during cranking is he? The starter on the car is controlled by the computer, so all you really need to do is give the key a quick flick to the crank position and let go and the car will continue to crank until it fires or times out after a few seconds (I want to say about five or so).

There could be many different causes for the problem although it does sound fuel related. Could be anything from a defective lifter pump, maybe even the mechanical high-pressure pump, or possibly an electrical/control issue. I'd start by taking it in if the car is under warranty and if it isn't, get it on a scan tool and check for codes and then watch the data stream to see what the fuel pressure is doing. No need to throw expensive parts at the car until you can narrow down and pinpoint what is causing the issue.

 

it was 01287 and 01278 i think i remember.

He is trying to turn it over, a quick flick (like what i do) does not turn it over when he fills up gas

 

Well dont jump to the conclusion it is the fuel pump, because this happened to me and it was because of EVAP emissons high purge flow fault. Tell him to wait for CEL's, and if it does come up go to the dealership they fixed my problem with it

 

Replace the EVAP purge valve on the intake manifold. $30.00 or so from any AC Delco supplier.

 

I have almost the same issue... tell your friend to try priming the fuel pump. I have to prime mine every time I start it. Basically turn your key to the accessory mode, buckle your seatbelt to give the fuel pump time to prime, then start the car... hopefully this will solve the problem...

If it does not, then look into some of the other ideas given here....

 

Apparently he described it as a surge valve. anytime he would open the gas tank it owuld suck in air. he got it fixed at the dealership then got a DUI and wrecked his car.

 

That sounds like a good explanation for the problem he is experiencing. The fuel pump in the tank maybe dying or there could be a leak in the fuel system that is causing that issue. Thus the HPFP maybe being starved. The reving I suspect is caused my the mix being super lean initially.