Manager Forum

Just worked on one a these yesterday. At 15 degrees ambient temperature the engine was running within 5 seconds of starter engagement.

Yea, focus on fuel issues and I feel certain you'll discover the problem. As I mentioned before, check the cam sensor signal. Does the scan tool see engine rpm when trying to start?

Well, tested fuel pressure and ICP...both good. Cam and rpm reading good. Battery voltage and cranking rpm good. Did I miss something?

Harnesses under v/c 's were good? Nothing loose or melted? I only see those, the ficm and the glow plug relays. Did you check the ficm?

Yup. All good. I wouldn't believe it if I didn't see it for myself based on the symptom. What is the best way to test the ficm?

Ive never repaired one. They say the reprogramming of it is to keep the turbo from spooling as fast? Thats the only thing the reprogramming is supposed to be used for. Im not sure what that really benifits.

I have some new info...

Doing some research on the buzz test. Did this test way back and it passed, however, half of the buzzes were real muffled. I didn't know at the time but apparently muffled buzzes indicated gummed up injectors. This coincides with the fact that the engine runs better as it warms up. I am currently warming the engine fully and will do another buzz test to see if it's better.

sounds like you're on to something here. expensive repairs like injector replacement makes you second guess yourself if you don't see it everyday.

I was talking to another shop that does some of the work on the ambulances, and he said that he fills the fuel filter housing with seafoam and runs it for a min and shuts it off and lets it sit for a couple hours and then runs it down the road hard and says it does a good job of cleaning the injectors.

Could be could be the harness also

Just did another buzz test warm. Much better now. Only 2 are muffled instead of 6.

liljoe wrote:I was talking to another shop that does some of the work on the ambulances, and he said that he fills the fuel filter housing with seafoam and runs it for a min and shuts it off and lets it sit for a couple hours and then runs it down the road hard and says it does a good job of cleaning the injectors.

I did this on a duramax and still ended up doing injectors

I ran this one by my piece. He had a 7.3 ps in his old flat bed.

this is how he says to test the glow plugs.
Put alligator clip from test light to pos post on batt.
take wire off glow plug, then PROBE the tip. if good plug it will light.

he said if you got 2 or more misbehaving plugs the relay wont cycle right.

liljoe wrote:I was talking to another shop that does some of the work on the ambulances, and he said that he fills the fuel filter housing with seafoam and runs it for a min and shuts it off and lets it sit for a couple hours and then runs it down the road hard and says it does a good job of cleaning the injectors.

We tried this on a Dodge/ Cummins and it worked well for us. The customer was amazed with the difference. I guess it depends on whether the injectors are just gummed/ varnished or hammered.

I have a feeling, given the info, you'll be replacing the injectors. But you have provided an interesting test issue. Doing the buzz test both hot and cold.

CHECK OUT YOUTUBE 7.3L LONGEVITY INJECTION TUNE UP 1 OF 4 THE OIL IN THE "HPOP" HIGH PRESSURE OIL PUMP THE OIL WHICH TURNS TO TAR WONT HELP THE INJECTORS OPEN WATCH THIS THERE ARE 4 PARTS TO THIS AND YOU WILL SEE HOW TO CHANGE THIS OIL E-MAIL FMD302@MSN.COM

Thank you Phil for the insight. I'll pass this along the vehicle owner and see if they want to try it.