7.3L 1999 Ford F550 Trouble Starting - Diesel Forum

sts73 · 07-12-2006, 02:51 PM

I am hoping you can help me. My boss has asked me to search the internet to find the solution to the problem with his truck. It was been in and out of the shop and no mechanice seems to be able to fix. The truck has trouble starting after sitting for a day or 2. They use it for a business so when it sits over a weekend it is hard starting on Monday morning, regardless of air temp. When starting it cranks over but won't start right away. Eventually it will. The injector loses oil pressure. It doesn't smoke, runs normal and has lots of power. The engine seems to be fine. The glow plugs have been test and connectors replaced. Oil in the HP oil reservoir has been topped off. The fuel tests all came back OK. Can anyone help me? Thanks!

wilson61 · 07-12-2006, 04:06 PM

get a small 12 volt light and wire it to the glow plug relay on the side that goes to the glow plugs i think it is the left. but check one side will be hot all the time the other only when the glow plugs are to be on. i leave one hoooked up all the time and it will tell you if the truck thinks it needs glow plug help to start and that the relay is at least picking but not 100% that the relay is good to carry enough current to heat it up. may not fix but it will give you some information . also look at the top of the questions for hard start or no start

sts73 · 07-13-2006, 10:20 AM

Thanks! I printed out the thread at the top but since the mechanics keep saying his glow plugs are OK he wondered if there could be another issue. I appreciate the help.

Clackmaster99 · 07-13-2006, 10:35 AM

sts73..........

You may want to consider having a diagnostic scan performed to assist with determining whether any codes have been capture/stored. A check engine light doesn't always have to illuminated the check engine light. Also a scan will provide valuable information and necessary parameters in an attempt to solve concerns.

GrampyJim · 07-13-2006, 11:08 AM

First, I'd get your boss to visit a shop that has some diesel experience.

For no start/hard start concerns, we will generally set up the scan tool to monitor what I have come to call the "no start PIDs" before I attempt to start the vehice for the first time. These parameters are V_REF (PCM reference voltage), RPM (engine RPM), ICP_V (injection control pressure measured in volts - an actual value), ICP_P (injection control pressure in PSI - *sometimes* this could be a substituted value if the PCM doesn't like something - it can take some experience to tell), IPR (injection pressure regulator duty cycle). Having this test performed should give the tech enough info to decide his next step.

Some idea of how many miles since last oil change and how many miles total might give a clearer mental picture of the truck.

If asked for a SWAG, I'd think that the high pressure reservoir is leaking down or the batteries get weak enough to lower cranking rpm.

In the end, nothing compares with a logical, step by step diagnostic process to reduce repair time and minimize needless parts replacement.