6.5 stalls at startup

[95-6.5]

Here is what happens.When i first go to my truck and start it in the am for the first time.It will usually die within 20 seconds.Just like somebody had shut off the key.It will do this for about 5 min.Constanlt starting and then dieing.Once it stays running it will run all day without and issue at all.When i park at work or anywhere else for longer than a couple of hours it will do th sam thing all over again.It will start up then die,start up run for 10-15 sec and die.I can have the throttle halfway and it will still die all of a sudden.This happens for a good 5 minutes of constantly doing this.But once it stays running it is fine.I have drove from dallas to houston and back with no issue.
It just seems that when i first go to start after a period of it sitting it constantly stalls.Truck is automoatic and has had oil,fuel filter,air filter changed.any ideas....I also have th green lable pump as well.Like i said after about 5 minutes of constantly starting,it will run without a hitch...I show no lights on the dash as far as check engine lights or anythig like that. :confused:

[ucdavis]

Green tag pump had some of the mods Stanadyne put in the DS4 eventually, but not all (I think the FSD has been updated since among other things). But it sounds like IP or FSD.
FSD w/ FSD-Cooler is an easy change-out (don't need to remove the FSD on pump if mounting new one on cooler). Trying a new FSD is the only way to diagnose this that I know.
It could be the fuel shoutoff solenoid on IP (cylinder sticking up on front left side) which is an easy R&R if you can get the part from Stanadyne dealer (diesel injection rebuilder in your yellow pages) but no guarantee that's it.
You didn't say if it had any error codes in computer; if it does you should post those for better diagnostic.
If it starts, a stall is likely only going to come from failed fuel feed, so I'd keep looking around the lift pump, filter, IP, injectors till possibilities are exhausted there.
Good luck.

[patrick m.]

95 is a great year for failing ignition switches.
mine used to do that, before the transmission symptoms showed up. i replaced the ign switch to cure the trans problem, and was blessed with no more stalling.
i should tell you my stalling was not as predictable as yours is, BUT, since you will most likley need one anyway, it wont hurt.
you can check each row of fuses in the fuse panel for full batt voltage during and just after cranking. there should be at least 10volts while cranking.
(mine would drop as low as 6 volts on some fuse "rows" while cranking.)
just something to check

[charliepeterson]

All good ideas. In the morning or when it sits for a while open the fuel filter and pull it out. The fuel must be at the top.
This condition sounds like it could be sucking air at start up. When the fuel system bleeds itself it runs good all day?
The pick up pump on the frame rail does supply plenty of fuel but it can take a short time to bleed itself. It can be tough to find an air leak on the suction side. Air can get in with out really letting fuel out. All lines up to the Injection Pump from the tank are on the suction side.
Does it matter how much fuel is in the tank for this to happen? We have a stand pipe going to the bottom of the tank, some times if this pipe cracks above the fuel level it can suck small amounts of air if the fuel level is below it. This is rare but it can happen.
I would follow all the fuel lines going through "P" clips along the frame rail first looking for small pin holes or rub marks.

[moondoggie]

Good Day!

Our '95 Sub was doing much the same recently; it would also stumble with WOT. I suspected the lift pump. As near as I can tell, the lift pump gets power two ways: through a relay (during cranking) or through the oil pressure switch/sender (during running). Here's what I did:

I have an old vacuum/pressure gauge, back from the days when folks used to analyze some engine problems with these. I connected a 3' hose between the vent port on the top of the fuel filter & this gauge; I opened the fuel filter vent 1/2 turn. I then put the gauge where I can see it when I turn the key. I set the parking brake, put the truck in any position except park or neutral, & turn the key as though to crank the engine. This causes the lift pump to run, but the engine won't crank.

The second test was to shut off the key, put the truck in park, & start it.

On our Sub, I developed fuel pressure during cranking (1st test) & none during running (2nd test). I replaced the oil pressure switch/sender. Now I develop fuel pressure in both modes of operation. No more stalling after starting, no more stumbling on WOT.

This may not be what's wrong with your truck, but I can do these two tests quicker than I typed them out, so why not? If it doesn't help you, maybe someone else...

Blessings!

Brian Johnson, #5044

[ 11-28-2003, 01:28 PM: Message edited by: moondoggie ]

[GARY PAGE]

Attach a Fuel pressure instrument to the bleed line and open the valve, start the truck and check for a minimum of 4PSI. I bet you don't have it. Fuse 8 in the I/P controls the crank relay which provides power to the pump under crank position but it drops out in run and Oil sending unit provides the bias. Check for a failed oil sending unit contact next or maybe first. Attach voltmeter to fuel pump is there voltage and no pressure if so it's the pump. I bet the truck jumps under hard pedal. My guess it a fuel lift pump pressure thing. Whens the last time you checked the filter? All of this stuff is in the stalling section in the members section.