03 - 7.3 Starting Problem

[SLAK]

Ok, it's time to stop lurking and ask a question. I bought a 03 7.3 PS ambulance with 212K miles that I am converting into a locksmith service vehicle. It runs good but starting is an issue. I finally figured out how to get it started but don't know where to look for the problem. When I turn on the key and wait about 45 seconds I hear what sounds like a small unprimed pump running. At the end of 45 seconds the noise stops or times out and I turn the key off for 6 seconds and try it again. After the third or forth time I do this, the pump changes to a sound like it is primed. I may be way off base here. But, when I try to start it, it cranks right up and runs great. By the way, I hear the fuel pump hit about 3 licks each time I turn the key on. I'm guessing but is it possible the fuel it draining back down the line and the small pump I am hearing is an injector pump? If so, does anyone have any idea where the leak could be. Working on this E450 cutaway is a nightmare.
Thaks for reading.

[NoRalPh]

I'm gonna guess that "unprimed pump" you're hearing is the vacuum pump on top of the pass fenderwell under the hood (take a look, you might have a leak).

As for the fuel pump itself (on the frame rail under the drivers seat), I don't think there's anything wrong with it clicking a few times once the system has pressure.

If you've been lurking I assume you've read;

Winter Operation, Hard Starting, Hissing Sound Etc...

&

Troubleshooting GPR & GP's

AND, being in TX, I don't think the GP system is essential to starting but it's a good place to begin...

[SLAK]

Dumb question follows:
What does the vacuum pump have to do with the engine starting? Is there some valve it has to operate to allow the engine to start?
These diesels are something else. I love it but being a gas person all my life leaves me in the dark. This is a real learning curve.
Thanks

[Six0~Stroker]

Do you have electronic 4x4 or the manual shifter on the floor...

Im assuming you have the electronic switch.

If so then the vacuum pump creates a "vacuum" to activate the 4x4...

Diesel vehicles do not make vacuum with the engine like gas vehicles do so they require a vacuum pump actually.




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[SLAK]

I have neither. This is a 2003 E450 Econoline Cutaway with an Ambulance box on the rear I'm converting into a locksmith service vehicle. It has an automatic tranny.

[Six0~Stroker]

Oh... my bad then.




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[NoRalPh]

Originally Posted by SLAK

Dumb question follows:
What does the vacuum pump have to do with the engine starting?

Absolutely nothing...

I'm thinking the noise you hear and the slow start could be unrelated.

Did you check the vacuum pump to see if it's causing the noise?

Did you verify the GP system is functioning properly?

[SLAK]

I opened the hood and could see absolutely nothing there except the AC fan blower and battery. I will pull the inside cowl (with all the ambulance electronics hanging on it) off tomorrow and check the vacuum pump. I've already done the GP testing a couple of months ago. Things were in order there. It was 85 degrees F here today and I went through the same process to start it. I'll let you know what happens. Working on these Econolines with to little hood is a rear bummer. Thanks for your help.