Hard Start Hot or cold.

[hubert3317]

I installed a Air Dog 100 thinking the stock lift pump was the cause of hard start.  It seams to be hard to start off and on. I dont hear the fuel pump come on and it is hard to start. I changed the fuel pump relay to a new one twice. if i turn the key on and off the fuel pump will come  on and the truck will start. I am lost and cant figure this out.

[MnTom]

Check the trigger wire for the relay. Maybe a loose connection in the relay socket? Sometimes the spade connectors open up and become loose.

[mopartechnician]

Put trigger wire to wiper fuse. Then come back if you are still having hard starts

[hubert3317]

Thankyou guys i will try this and let everyone know how it works

[hubert3317]

quick question for everyone. How long does everyone recomend waiting until you try to start the engine?

[MnTom]

Usually until the "Wait To Start" light goes out.

[hubert3317]

 Okay i was just making sure no one waited longer than that. I put in the wire the air dog runs all the time when the key is on but i drove the truck about 4 miles than parked it and shopped for about 24 min. when i came out and started the truck the light went out and than started to crank it and it cranked forrever before it started. what else can i be? Once running it runs great lots of power and no troubles

[MnTom]

Quite possible you are going to be needing injectors. Once one or more begin to fail they give the same symptoms you have. Try plugging it in for a couple of hours and see how it starts. If it starts good then you are looking at injectors. Do yourself a huge favor IF you need injectors by replacing all of them instead of trying to find out which one is the bad one. If one is failing the others are not far behind.

[hubert3317]

IF it is needing injectors will that make it smoke (black) really heavy sometimes and not all other times? Expecially smokes bad if it idles at for a little while after its warmed up.

[MnTom]

Entirely possible. What happens to make it start hard is there is too much return fuel and the rail pressure is low. You may have an injector that is beginning to slobber too.

[hubert3317]

Does the fuel pressure go low and the return go high because the injectors are not Giving it the fuel?? IT has 75000 miles on it but i put the air dog on when i bought at 72000. If one is slobbering like that make it smoke intermitently

[mopartechnician]

If its still hard starting, most likely you have too much injector return. Its bleeding the rail pressure back into the return and isnt letting your fuel atomize correctly. Try taking all the injector lines off and torqing the connector tube nuts to 37 ft lbs.

[MnTom]

From what I have learned there is a chance of some engine damage with high return rates at starting due to the fact it could be dribbling fuel when cranking and through out the running of the engine. Without pulling and testing the injector(s) it would be real difficult (IMHO) to pin point the exact cause. It could be any of these causes:
Worn injector ball seat
1. Leaking cross feed tubes (Cummins)
2. Blown internal high-pressure seal
3. Incorrect nozzle needle clearance
4. Cracked nozzle body
5. Cracked injector body

[mopartechnician]

No it will not cause any damage. There is an injector return test. If he had an injector leaking into the clyinders, he would have smoke and a crank case full of fuel

[hubert3317]

I dont have any gray or white smoke at idle or ever just the really hard starts. With the pump jumpered it seams worse now. Where should i go now?

[hubert3317]

In a new development it only does it now when it is hot? DO i need to take it to get it tested or is there a way i can do it?

[mopartechnician]

You gotta have a special tool to do the test. I would torque the connector tube nuts first and see if that helps

[hubert3317]

I will try that in the morning and see what happens and let you know. thankyou for your help

[AH64ID]

The fuel pump won't always run when the motor is hot, it just runs for a few seconds at most unless it's really cold. Then it will run for up to ~30 seconds. 

 

When it doesn't come on at all try bumping the starter, go to start for a split second but dont start it. Does that make it work?

[hubert3317]

Injectors and cp3 tested good and the lift pump is running good. Still sometimes just cranks over over and over. What else  could it be?

Edited May 14, 2014 by hubert3317