92 F250 7.3L IDI fuel system componets please.. - Diesel Forum

Kaliburz · 01-07-2008, 12:43 AM

An intermittent issue here w/ buddies truck again. Block heater is fixed, warming nicely, but this issue seems to happen even when he runs into the store (w/ a HOT engine).

Some times, he turns ignition, glow plugs signals waits, then goes off and he cranks. And he cranks. It takes a full 5-10 seconds before the truck 'starts'. Other times, it starts almost instantly. Plugged in or not, it seems to do it.

I told him to leave the ignition "on" after glow plugging for 5-10 seconds longer, just in case there is an in tank fuel pump- prime system.

So, what are the components of the IDI fuel system? An in tank pump, mechanical engine fuel pump and then injector pump? IT acts like it has no fuel (loosing prime, sounds funny I think). Is there an in tank pump?

arthurgoboom · 01-07-2008, 01:10 AM

The IDI fuel system consists of a mechanical lift pump on the passenger side front of the block, and the high pressure injection pump. There is no in-tank pump. Hard starting with a hot engine on the IDI is usually a sign that the injection pump is getting worn out and it won't build enough pressure to properly fire the injectors at cranking speed. They are usually ok once you get them started though.

Kaliburz · 01-07-2008, 03:43 AM

Uh oh. Don't think the bud will appreciate hearing that.

Man, this truck must have been abused prior to him getting it then. The odometer read 130,000 when he got it- and it's just under 140,000 right now. Has a ATS turbo system. There was signs of a 5th wheel set up, so it has doe some towing, how heavy, no idea.

I guess we'll change the fuel filter and keep the fingers crossed.

cdnsarguy · 01-07-2008, 07:26 AM

There could be a bad air leak into the fuel system but other signs would be visible......white smoke.

Do a pressure and flow test of the fuel pump at the Schrader valve on the filter header (FSS- fuel shutoff solenoid disconnected on IP). Remove the tire valve core and hook a hose and pressure guage on it should see 4-6 psi when cranking. Then do a fuel quantity test same place, should see 1/3 pint in 10 seconds of engine cranking, route fuel to a suitable container with a hose.

If there is a problem with the lift pump and you are changing it, ensure the new pump comes with instructions as to correct installation procedure if it is the newer model pump with the almost straight arm.

Visit......http://www.intellidog.com/dieselmann/idi.htm .....and do some fuel system reading........

WilsonJ · 01-07-2008, 10:45 PM

Intelidog is a good start, a real good start.
I went through a similar set of problems mine resulted from air seeping in through the return lines and injector O rings.
It's 30 bucks in parts and a long day of fiddeling with injectors and stuff but it may be worth a shot before you go after the IP. Also my dealer mech did the lift pump at the same time, I credit that to me abusing it, runing it when it wasn't primed.
I was feeling my way throught the process when I finally turned it over to the pro's.<my other half finily had it and put her foot down - on my throat>
I will say this when I was doing diagnostics I used a mighty vac with the catch cup on nearly everything I could touch. I knew it was the return lines when I could pull a strong vacume on the drivers side but not on the passangers side. The other thing that was mentioned to me was that is a huge tip off to it being the injector return loop is if your seeing a small puddel of diesel in the well(s) on the manifold right by the injector(s). I use to have a real issue with refusal to start so I started by using the MVac to pull the lift pump prime (very noticeable air bubles). Well that's just my experience with a 92 350 7.3 liter that had 149k on it at the time - It did spend it's 1st 100k as a work/plow truck and it seems to have been beaten on a bit too.
I know that's a bit of a scrambled tale there but the point is if it is in the O-rings/Injector return loop the air is getting into the system either alot over night or alittle like when getting milk and eggs. It is not really enough air to noicably effect the running motor but will screw you up at start up. Mine got so bad it would cause me to stall at points,(typically after a long hot soak) and was real tuff to get back going. Any thing more I can do feel free to hit me up.