24V Hard Start But Runs Perfect - Please Help
#21
03-02-2008, 12:42 AM
What determines if it turns on or not? Is it the ECM, a relay, or a switch? When LP doesn't turn on and I try to start the truck it will turn over for several minutes before finally starting. When I turn on the ignition as describe earlier and the LP eventually starts, the truck will start instantly. I'm an electrician by trade not a mechanic, maybe I'm looking at it from the wrong perspective but somehow it seems connected. Thanks
#22
03-02-2008, 12:45 AM
I've been following your posts for the past couple of days, it's the reason why I became a member tonight. I've been having the same symptoms as you have. I also have a 99 24v 2500 w/76k miles, but I don't have any modifications to the fuel system. My hard start problem seems to be associated with the LP not turning on. When I place my key in the ignition and turn it to the on position prior to making the engine crank over my fuel system relay clicks. When I crank it the LP pump doesn't turn on as it's supposed to, or rather, it doesn't turn on every time. In the morning I have to crank it once, wait for the buzzer to stop then listen for the LP pump, if I don't hear it I pull the key out and try again. I usually have to do this a dozzen times before it works. If I continue to crank the engine it will eventually start after a couple of minutes. I'm assuming this is because the VP is doing all the work building up sufficient pressure which will eventually burn it out. I tested the voltage going into the LP and got 12vdc for the first second after cranking the key then the voltage dropped to 8.5vdc. When I did this test, I had run the truck earlier that day so whatever the problem is could have been masked, I will try this test again first thing in the morning. Regardless, I purchased a new LP, stuck it in, primed it, and I still have the same problems.
Other than the fuel system relay, are there any other switches that could block the voltage from getting to the VP, i.e. low pressure, water in fuel, other relays? I haven't been able to find good wiring schematics for the fuel system, does anyone have them? I can jumper my LP to my battery, throw in a switch, and it will work but it won't fix the problem. I hope it's not an ignition or ECM problem. MikeyM, do you hear your LP when you first start it in the morning? Hopefully we can help each other.
Thanks, Aaron
Other than the fuel system relay, are there any other switches that could block the voltage from getting to the VP, i.e. low pressure, water in fuel, other relays? I haven't been able to find good wiring schematics for the fuel system, does anyone have them? I can jumper my LP to my battery, throw in a switch, and it will work but it won't fix the problem. I hope it's not an ignition or ECM problem. MikeyM, do you hear your LP when you first start it in the morning? Hopefully we can help each other.
Thanks, Aaron
I may be remembering wrong but I think it's between 1 and 2 cups of fuel you should get from bumping the starter.
#23
03-02-2008, 11:10 AM
I don't have many clues about the vp44 pump, do repair cav pumps, kind of similar build, 1. they both have a build in feed pump.
On the cav on hard starting, ( starter battery is OK, spin fast enough to start ), remove end plate, clean that, install new filter ( yes filter in pump ) replace paddle wheels, made of carbon, replace rear plate, bleed system, engine fires up, usually fixes had cranking both cold and hot on a good engine there don't have other problems, like injector or low compression.
On the cav on hard starting, ( starter battery is OK, spin fast enough to start ), remove end plate, clean that, install new filter ( yes filter in pump ) replace paddle wheels, made of carbon, replace rear plate, bleed system, engine fires up, usually fixes had cranking both cold and hot on a good engine there don't have other problems, like injector or low compression.
#24
03-03-2008, 02:57 PM
Another Update:
So after the FASS HPFP install, my fuel pressure is now @ 16 psi idle, 15 WOT - one less thing out of the way. But onto the continuing hard start issue..
So check this out. About an hour ago, after extended cranking and no start, I got another P0336 code - I just changed the CP sensor. I've read about the wiring harness rubbing through or connectors getting dirty or oily and gumming up. Any idea where these connectors are? The one on the CPS was pretty clean. I head the AC is on the same circuit? Any particular connector or area where the harness would rub?
Again, once the darn thing starts it runs great. I do notice a seemingly heavier puff of black smoke on start and the battery guage seems to say the battery is charging at a little bit higher rate than it used to.
Any ideas?
Thanks for your continued patience, Mike.
So check this out. About an hour ago, after extended cranking and no start, I got another P0336 code - I just changed the CP sensor. I've read about the wiring harness rubbing through or connectors getting dirty or oily and gumming up. Any idea where these connectors are? The one on the CPS was pretty clean. I head the AC is on the same circuit? Any particular connector or area where the harness would rub?
Again, once the darn thing starts it runs great. I do notice a seemingly heavier puff of black smoke on start and the battery guage seems to say the battery is charging at a little bit higher rate than it used to.
Any ideas?
Thanks for your continued patience, Mike.
Last edited by MikeyM; 03-03-2008 at 02:59 PM.
#25
03-03-2008, 05:24 PM
Banned
What determines if it turns on or not? Is it the ECM, a relay, or a switch? When LP doesn't turn on and I try to start the truck it will turn over for several minutes before finally starting. When I turn on the ignition as describe earlier and the LP eventually starts, the truck will start instantly. I'm an electrician by trade not a mechanic, maybe I'm looking at it from the wrong perspective but somehow it seems connected. Thanks
The 15 percent duty-cycle is used to limit injection pump inlet pressure until the engine is running.
The transfer pump is self-priming: When the key is first turned on (without cranking engine), the pump will operate for approximately 1/4 second and then shut OFF, But Not Always. The pump will also operate for up to 25 seconds after the starter is engaged, and then disengaged and the engine is not running. The pump shuts OFF immediately if the key is ON and the engine stops running.
#26
03-03-2008, 05:32 PM
The '99s don't have a cam position sensor, do they? After replacing the CKP sensor only to have the code come back today, I'm down to checking the wiring harness or something else.
Note - The other day when I tried to start it, It would crank faster and faster and faster until it sounded like a gasser trying to start. I released the key, waited and tried again and it fired. Still, no white smoke or any of that stuff.
Thanks, Mike.
Note - The other day when I tried to start it, It would crank faster and faster and faster until it sounded like a gasser trying to start. I released the key, waited and tried again and it fired. Still, no white smoke or any of that stuff.
Thanks, Mike.
#27
03-03-2008, 05:38 PM
Banned
On a 2002
The Camshaft Position Sensor (CMP) performs multiple functions. One function is to detect engine speed (rpm). Another function is to relate crankshaft position and Top Dead Center (TDC) of the number 1 cylinder. Because the CMP is now used to relate crankshaft position, the Crankshaft Position Sensor (CKP) is no longer used.
The Camshaft Position Sensor (CMP) performs multiple functions. One function is to detect engine speed (rpm). Another function is to relate crankshaft position and Top Dead Center (TDC) of the number 1 cylinder. Because the CMP is now used to relate crankshaft position, the Crankshaft Position Sensor (CKP) is no longer used.
Last edited by DB Admin; 03-03-2008 at 07:38 PM.
#28
03-03-2008, 07:36 PM
No cam sensor on a 99 - just the crank position sensor, which I see youve already replaced.
#29
03-04-2008, 10:51 AM
when you changed the ckp did it have a groove in it, if it did the tone ring could be loose and no matter how many sens you change they get ruined quickly
tightening the tone ring isn't the most fun job in the world
tightening the tone ring isn't the most fun job in the world
#30
03-04-2008, 11:15 AM
More info please if you have it. Thx.
