starting voltage ?

[Tractorat]

Can anyone tell me what the starting voltage needs to be in order for all the computers to be happy and know they are supposed to be turned on ?

 

[Tractorat]

I meant minimum voltage.

 

[KATOOM]

I dont know what the computers require but I was to understand the VP requires no less than 9 volts for the fuel solenoid to function.
Why are you asking?

 

[DonFitzwater]

Whadya got going on?

 

[Tractorat]

Ive been having an intermittant hard start. Its acting like its did a couple times a couple of years ago. Couple years ago it turned out to be a crack in the cap on top of the fuel tank. Last year it was batteries.
I checked the voltage the other day when I had the problem and the overnight voltage was 12.6 and dropped to 12.2 when in the on position. Hard start then. But I checked the voltage this morning with same voltage results and it started right up. ( If the wts lite came on, I didnt think to notice).
I put the charger on the batt the other day for a few hours. It wasnt at 100%, but it was charged. Had the hard stard issue (always starts on the 2nd try, but long cranks for both)
(Yesterday morning the overnight charge was higher than today)
I did fill the tank on thurs and havent had a problem yet (coincidence ?), but I havent driven hardly at all either. If it is a loss of prime issue, can having less than half a tank cause an issue to show up that wouldnt show up with a full tank ?

 

[DavidC]

What year are we talking about ?

 

[BigPapa]

What year are we talking about ?

From his profile page:

2002 2500QC SLT, 4x4, 3.54, short bed, automatic, EZ box, boost pyro and fuel pressure gauges, 4" exhaust system

 

[DavidC]

So if you bump the starter without trying to start what is your fuel pressure ?. Pump should run for 30ish seconds.

 

[Tractorat]

I havent done that yet. Next time I have a hard start Im going to.

BTW, when it starts with the hard start, the fuel guage fluctuates wildly from about 13 or 14 lbs to about 16 or 17 lbs and keeps that up for a while. Normally it just flutters just a little bit. I havent driven it enough in the last few days to see if it will stop the fluctuation if I just keep driving. But if I shut it off and start it maybe a couple of times the guage will act normally.

 

[Tractorat]

So if you bump the starter without trying to start what is your fuel pressure ?. Pump should run for 30ish seconds.

15 lbs. Started it this morning after letting it sit for 2 days with less than half a tank of fuel. Hard start. I bumped the starter 3 or 4 times and it started right up. But it took those 3 or 4 bumps to get an immediate start. Otherwise it wanted to crank for a while before it would start.

 

[DavidC]

Sure sounds like a leak, you had 15psi right off the bat ?. Be sure to check the banjo on the back of the head and the T not far from it where the return from the VP and head join to return to the tank, that seems to be a hot spot. These are very difficult to solve and I have seen the fuel tube o-rings have leaks, the VP bypass leaks, it goes on and on and most just start changing parts if nothing apparent shows up.

 

[Tractorat]

Thanks, yeh, probably a leak. It seems like it takes 2 days of sitting to cause a problem. Can the fuel level in the tank (full or less than half) have anything to do with it ? Or make it worse ?

 

[DavidC]

Thanks, yeh, probably a leak. It seems like it takes 2 days of sitting to cause a problem. Can the fuel level in the tank (full or less than half) have anything to do with it ? Or make it worse ?

Probably only if you have a pick up tube problem. You can keep the tank full to test that theory, others have parked on a hill with the nose down or on ramps etc. to see if fuel is actually being sucked back to the tank. There have been reports of the 90 on the top of the module having pin holes also.

 

[Tractorat]

Thanks,
I have a sump at the bottom of the tank so probably not part of the issue. I just wondered if there was some kind of return that might be affected by the tank level.
Im going to call the shop tomorrow or monday if they are closed to get it in. I just want to set up any conditions I can that will make it more likely to fail while they have it.