Hello folks.
Long time lurker, needing some help now.

I have a 95 3500 12v cummins that is exibiting hard start problems & I have looked all over, but I cant seem to find a matching condition.

OK, so here goes.

I go out and hop in my truck, turn the key, wait for the wait light to go off, Hit the starter and she spins up like she should. But she wont start and run. Usually it will fire and then die.

BUT if I go out, and follow the same thing, and hold the throttle 3/4 to full down, she will fire up rather quickly (2-3 revolutions), blow some heavy fuel smoke (Due to full throttle) and away we go.

Now I know this is the COLD START proceedure, but I have to do this even in the summer. And I need to do this almost EVERY time I restart my truck. Start at home, tromp it, at the store, tromp throttle, stop for fuel, tromp throttle....yada yada. I have gotten to the point that I do it every time, just so I dont end up stranded due to a weak battery from all the restarts. If I loan it out to a friend, explain the way to start it & they forget a couple of times, and then its a royal pain to get going, because then the voltage is low enough that I think the solenoid fails to open. Once the battery is up, its good again.

I have good power, good idle speed, no issues with it dying (unless I forget to depress the throttle, it till fire off and die immediately)

Intake heater is cycling as it should, I can hear the click and see the voltage pull down during cycle, and if its cool, you can tell a difference in the engines starting.

I dont think its a loss of prime because it fires off almost immediately if I do the depress throttle thing, and I see no signs of seepage anywhere.

Not sure about shut off solenoid because it does fire if I work the throttle, and I would think the solenoid would block the fuel off no matter what I did with the throttle.

filter restriction should still be restriction because its supply to the pumps and I see no performance issues once its running.

Any ideas?

 

what is your idle speed?, it should be about 850 rpm's, and to slow of an idle always causes this issue, if you need to turn it just adjust the low idle screw in the pic (its the driver side rear of the injection pump

 

Don't discount the fuel shutdown solenoid. The linkage can get dirty and fail or hangup during actuation. To eliminate it as a problem do this, before starting, turn the key to on. Then lift the solenoid manually to the on position. It should hold in the on position and also pull it up all the way. Now try starting. If it starts easy then that may be your problem.

The solenoid had a rubber boot to protect the linkage. lube the linkage and see if it helps. If this does not help at least you eliminate the solenoid as part of the problem.

 

Well, its about 700-750 by dash tach. Looks like I may need to bump it up after the holidays. So Im shooting for 850? Didnt realize it was that high. Too many Cat industrial engines hahaha.
From the drawing it looks like a bump stop, so I need to run it in to raise RPM right?
Ok, I have a phototach in my box at work so I can get a definite true reading when Im ready.

Just looked at my truck and it looks like I'll have to do some stretching exercises before I try to get to it hahahaha.

 

Ok, I will give that a re-look too, thanks for the tips.

I will try and get back after I do these things to let you guys know how it went. for some reason today EVERY time I do anything here I have to log in. View post, log-in, reply, log-in, submit, log-in, yada yada, log-in.

 

yep you want 850, the actual spec on it is 800-850 with a/c on and in gear(auto) but i found 850 warm idle is just fine, for what ever reason, when they drop to 750 or so they dont like to start, biggest thing is the throttle stop wears a little over time dropping the idle, but you want to break the jam nut loose, and back out the stop to raise rpm's

 

How would fuel pressure effect this issue? i.e., loosing fuel pump. I have set my idle lower than 850 and need to bump the throttle a little during start, but recently find little bigger bump on throttle required in cool weather. What got my attention was it felt like pedal went to the mechanical stop on the high end.

Maybe I should ask how would one know when the fuel pump is getting weak?

Thanks in advance.