P0300 Code After Wash - Now Start, Idle, Die ?

ClydesdaleCowgirl · August 2, 2008

Some Help Needed Please. 2001 2500HD Crew V8 6.0L 90,000Mi

Truck had issues starting and would usually take 5 or more turns to start. Decided to turn the key to prime it a few times before cranking it and that seemed to help.

Took truck through carwash that had undercarriage and all was fine until driving it down the road home when it started to lose power. Got to a signal and truck was idling horribly. Made it home and it sat overnight thinking water got somewhere.

Next day went to start truck and it started right off...idled and rocked badly...then died. Started again right off and I pressed the accelerator to the floor...it died down to a bad idle again... and died.

All hoses were in tact and changed the fuel filter (which seemed to help some) but still the hard idling and then a backfire occurred once after the filter change.

Took the truck to the local mechanic who ran and got the code... and said everything looked fine to him. He states that it's most likely the computer and it may need to be replaced or it has 'lost the ability to control the fuel injectors.'

After reading other posts about this issue, I checked the fuel regulator hose and it is dry. Any other ideas for me to check before I even look at the computer??? I have very little funds to fix my truck and I just got it 6 months ago (from a large dealer who, supposedly, did a great used-car check). Ugh!

Any help is appreciated!!! Thanks!

c]:o)

minibike132 · August 2, 2008

He states that it's most likely the computer and it may need to be replaced or it has 'lost the ability to control the fuel injectors.'

This is most unlikely and unless he did something more than hook up a scan tool the last thing I would condemn is a PCM. Can you have someone check fuel pressure. Check key up pressure, running pressure and how much drop is recorded over 1 minute after key up pressure.

who, supposedly, did a great used-car check). Ugh

We don't have a crystal ball in the inspection bay, you can see what might go wrong with some things like suspension or brakes but this doesn't sound like one of them. Some dealers will help out in this situation, have you contacted them?

ClydesdaleCowgirl · August 4, 2008

-The 'Crystal Ball' would be nice, but to make it clear = I only have issues with dealers who try to pull a fast one over on the consumer... otherwise, I have no problems with them or their employees. -

As for your help on the pressure test, the mechanic I took it to states that the fuel pressure is within specs - no exhaust restriction either. The truck starts fine and now will stay running but very lean. The only way to explain it is that every 2 or so turns of the engine, it drops to almost stalling.

Any other ideas from anyone?

Thanks!

minibike132 · August 4, 2008

What were the codes?

ClydesdaleCowgirl · August 5, 2008

The only code listed was the P0300...and no idiot lights on the dash at anytime either.

mndadof3 · August 5, 2008

P0300 is a random cylinder misfire. Have you checked the spark plug wires that go from the coils to the plugs for moisture? How about the coils themselves to make sure they are not cracked. With 90K, the plugs themselves are probably pretty worn (100K tune ups are a myth) so it is time to replace those too. Fuel pressure regulators do not always leak through the hose and if you are having that much problem getting it fired in the morning, the pressure regulator is a very common problem and about 1/8th the cost of a fuel pump. You'll probably benefit from replacing it even if it isn't bad, the new designs are built much better. Make sure to use di-electric grease when installing the spark plug wires so that water can't get trapped in the connections causing a misfire.... Good luck and keep us posted.

ClydesdaleCowgirl · August 7, 2008

Thank you!

I will check the list and see if the plugs were changed when I had purchased the truck. I will check the coils and I had already thought of replacing the Fuel Pressure Regulator... might as well right? If those don't work...on to the next step.

Thanks!

bossier62guy · August 7, 2008

Thank you!
I will check the list and see if the plugs were changed when I had purchased the truck. I will check the coils and I had already thought of replacing the Fuel Pressure Regulator... might as well right? If those don't work...on to the next step.

Thanks!