Follow up on No cold advance on Mech. IP Help please.

[BuffaloGuy]

Short review. '93 mechanical IP experiencing hard cold starts since pump turned up and reinstalled on new motor. IP cold advance is suspect and the following has been done...

UPDATE:
I removed the hose from the top of the IP as instructed, installed a long one with a hose clamp and daylighted it into a bucket. Also added an extension on the stub of the hose that now went to the fuel return line since I wasn't sure if it would spout any fuel.

I fired it up. Tested for power at the timing advance lead. All good. I had a very, very small stream of fuel coming out the line from the top of the IP. If it was any slower it would turn to a drip. DOES THIS SOUND ABOUT RIGHT?

After the motor warmed and the fast idle kicked down I pulled the timing advance lead off the pump and put power from the battery to it. Again, I could hear an extremely slight change in pitch. No noticable difference in the fuel running into the can. DOES THIS SOUND ABOUT RIGHT?

No fuel came from the fuel return line. I could blow thru this line (with the motor off) but it took some effort.

Any Ideas?
Ken

[britannic]

Doesn't sound like the HPCA is working right, because the IP housing pressure is around 12psi with the HPCA turned off and that should produce a bit more flow in the return line than you're seeing when it's activated.

How old is the pump? The lift pump and the IP's transfer pump also play a role in how much pressure is in the housing. Do you have another HPCA solenoid and/or HPCA regulator valve you can try?

[BuffaloGuy]

Thanks Britannic. The IP and the lift pump both have about 120,000 miles on them. I have a fuel pressure gauge mounted permanent and the lift pump seems to be fine. ABout 6 psi at idle. 5 psi at 70 mph empty.

I don't have a HPCA solenoid and/or HPCA regulator valve. What do you suggest? Would a wrecker have them. Or should I buy new?
Ken

[britannic]

With your IP pushing 120,000 I would recommend getting it rebuilt. I found Tim Wagner's rebuild service (he advertises in the classifieds here on the DP) to be very economical and his customer service is second to none - let him know you're a DP member:

Accurate Technical Services LLC
8768 N Centerline, Bitely, MI 49309
Phone: 1-231-598-1227
Fax: 1-309-294-9117
E-mail: tim@cleaninjectors.com
Websites: www.cleaninjectors.com (http://www.cleaninjectors.com) www.accuratediesel.com (http://www.accuratediesel.com)

[BuffaloGuy]

I called Tim and talked to him. Great guy. He had me remove and inspect the hose fitting(s) that are on the top of the pump. I always thought it was just a simple hose fitting but it is not.

Mine was a 2 piece (I guess there is also a 1 piece style). The upper part (the one the hose fits to) contains a little glass ball seated under spring pressure towards the IP.

The lower piece has another check valve that is also seated under spring pressure to the IP side.

Then under this fitting, inside the housing, you can see the small wire plunger that is the working end of the solenoid. When power is applied to the corresponding spade on the outside of the pump the push rod (not really a rod cause it is so small) pushes up on the bottom fitting check valve.

My 2 fittings did have some junk in them. It looked like it was pieces of thread sealant. I cleaned them good and replaced.

Fired up the truck and tested the flow out the pump. There is now more flow than before but when applying power to the spade the change in diesel rattle is about the same as before (not much).

I'm wondering if perhaps my truck was timed with the junk stuck in the fittings. This would have changed the timing and possibly there is no advance left.

Tim agreed with Britannic that at 120,000 miles on the pump it is probably not long for the world so I am not going to replace any parts but will get the timing checked again if not too expensive.

To rebuild my pump he charges $375 and it takes about 1 week. Not too bad. But I'll try to get all the life I can out of this one first.

Sorry for the long post but I thought this info might be useful for the next guy.
Ken

[britannic]

Using a timing meter will allow you to check the HPCA at the same time as setting the IP. The HPCA fitting you have is the later (1991-) design that prevents drainback when the fuel contracts during cold weather.

Try checking the button/plunger at the bottom of the IP on the pass. side is being actuated by the throttle when moved. If the plunger stays in, it will keep the timing advanced.

Just a thought, but if you found thread sealant in the HPCA, then there might be debris inside the pump as well.