testing MFI pump?

david482 · 06-29-2007, 11:22 AM

I have read through all the documents posted relating to the MFI pump and am trying to see if I can test mine by moving the rack. There was a black plastic cap just above the pump sprocket on the back of the pump, I removed this and there appears to be the hole that was mentioned. When I place a dowel into that and try to push nothing happens. Am I checking the wrong spot. I cannot see to find a picture of exactly where this hole is. Also dose the probe need to be very narrow, what I am using fits in the hole but maybe it is to large. The car will run at idle so I expected to at least be able to move things a little bit. Any suggestions would be great.

BURN-BROS · 06-29-2007, 01:47 PM

David,

You have to move the throttle arm and feel your dowel move. The rod may move the opposite direction(outward). Typically if the pistons in the pump are free(moving fuel to all injectors) then the rack will be free as well. A stuck piston is what keeps the rack from moving. The rack should move out then return on it's own.

david482 · 06-29-2007, 04:24 PM

well I looked at both sides and all the pistons seem to be moving fine. When I try to push the rack it moves a very small amount but never returns even if I play with teh throttle. Should I soak the inards with ATF ect., or am I looking at a rebuild?

BURN-BROS · 06-29-2007, 05:43 PM

As quoted from EarlySMan...Soak the MFI pump in Berryman's B-12 Chemtool for a few days ... it usually frees up without having to do any dissassembly or adjusting at all! After freeing up, let the pump dry out ... then soak in Marvel Mystery Oil ... and turn it over a few times every day for a couple of days.

Unless the pump is leaking or ran out of oil, etc just do what is prescibed above and run the pump. I would mix some marvel in your gas to help lube the pistons. Everything should free up once you get up to operating temps.

Do a search for "cma" to make sure your linkages are not longer/shorter than spec, etc.

david482 · 06-30-2007, 04:20 AM

Thanks for the info. I will start soaking and see how it goes. On another note. I know that when I put the pump back in the engine needs to be at a specfic point, no problem, but there is supposed to be a mark on the back of the pump and on the sprocket that need to be aligned. Msybe after I clean up the outside I'll see it but I have tried and just don't seem to see them. Are they very faint?

BURN-BROS · 06-30-2007, 01:43 PM

The Marks are distinct but not painted. One is on the steel bearing retainer @ 12 oclock and the other is on the smooth part of the pulley closest to the retainer.

david482 · 07-06-2007, 08:14 AM

I have removed the pump and have been soaking it, the insides, in B12. After about 24 hours I drained it and it was pretty gunky. I am going to refill it with clean B12. After I drained it the pump does not seem to turn as smoothly as it did prior to the soaking. The rack still does not move at all when I push on the pin, it moved once and has never returned no matter what I turn etc. I have soaked it on one side and will turn to on the other side tonight with clean fluid. I do not have a way to submerge the whole pump. Should I have seen some improvement by now?

356RS · 356RS's Garage

David,
The B12 is a cleaning solvent and not much of a lubricant. This might be why the rack is still a little sticky. After the second time of B12 cleaning and flushing, then the Marvel Mystery Oil added, you should then see better results with the rack movement.

david482 · 07-16-2007, 06:30 AM

Thaks all. Afeter the long saok with B12 the rack seems to move like it should. I am now soaking in Mystery Oil.

Once I drain that can I just add the motor oil prior to re-installing or is there something else I should do to remove the Mystery oil.

BURN-BROS · 07-17-2007, 07:30 PM

Marvel is a great additive for the fuel and oil of a MFI engine. Don't worry about the residue in the pump.