MFI Stuck or other malidies?

[Gearbox]

Need some diagnostic help. Last year the last drive around the block in my 1971 S I had experienced some throttle problems. Engine started to die out. Would start up right away and rev, but soon as I started to pull out again, it would stumble and then shut off. Not having the time and it was getting real cold, I decided to garage it and figure it out later. Well now is later. But a new symptom seems to have arised. No fuel to the injectors therefore no start. Here is what I checked so far:

Fuel pressure: About 13-15 PSI from the fuel filter
Spark and plugs: Good
Fuel to MFI: Good, same 13 PSI
Fuel to injectors NONE under cranking or otherwise
Shut off soleniod Appears to stroke when 12v is applied, off when cranking

Since I am getting good fuel pressure to the MFI pump and nothing is coming out to the injectors, it appears that something may be stuck in the pump. I know there is a fuel rail that the soleniod engages on deacceleration to shut off fuel flow, but what is the best way to get to this? Could it be this? Could it be clogged? Best place to start checking? Big hammer? Any help? Thanks Allan

[edmayo]

I'm curious where you are checking the fuel pressure at that you're seeing 70 psi. Can you tell me exactly which line. Irregardless if you have fuel into the pump housing, but aren't getting anything to the injectors that is also curious. Have you checked to see if the rack is moving freely? Pull the rubber plug off the back of the pump (above spur gear on back side) and use a pin punch to stick in and push against rack. The rack should be able to be pushed in and then spring back when released. Then you can also remove the side cover (the one just above the oil inlet) and rotate the engine by hand, you should be seeing the the individual pistons moving up and down.

[Gearbox]

Hi Ed, My mistake, it was 13-15 psi at the filter outlet (side of engine before it goes into the MFI). Thank you for the description of what to look for. That was exactly what I needed to get started. I believed the soleniod engaged the fuel rack to shut off flow on deacceleration, but didn't know where to access it. Also I was eyeing the side cover as a point of entry, maybe some carb cleaner? Thanks again and I'll let you know how it works out, Allan

[orange911]

Don't use carb cleaner inside your pump. That is where lubrication occurs and recirculates back to your oil tank. If you can not get it "unstuck" if it is, then you should take it off the car and clean it while disconnected and manually work the rack and rotate the cam. I think the cleaner of choice is either Marvell's mystery oil or more aggressive Berryman's B-12 (carb cleaner). Make sure you clean it out well before reinstalling. Make sure you know what you are doing before taking it off.

[Flieger]

Be prepared for a good bit of oil to come out of the pump.

[Mr9146]

Sounds to me like your pump is doing a death rattle. This is what two of my pumps have done before I sent them off to Gus at Pacific for a rebuild.

[Gearbox]

OK, got to the cap on the back and pulled it off. Put a .25" punch in the hole and tried to move it. It didn't budge. A few taps with a hammer and it still wouldn't move. I assume this should move in and out freely? Got the side cover off and ran out of time. But didn't see any access to rack. Anyway of moving it from the access panel or the back? Thanks Allan

[edmayo]

Yes it seems like the rack is stuck, it should have moved freely when pushing with the pin punch. You can try to free it up by using a pair of pliers on the clamp bolt of one of the pistons. GENTLY try to rock the clamp bolt back and forth. If it seems like there is some movement squirt some carb cleaner onto all three pistons and continue gentle rocking motion. It would be best to do all six pistons, but the other side pretty much denies you access unless you remove the the intake stacks, which although that isn't a big deal lets try from one side and see how it goes. If this is just lightly gummed up from the old gas this might get the rack freed up. If none of this works the next step is to remove the pump and work with it off the car where you have better access. Then you'll have access to the other three pistons, and you'll need to remove the check valves to get the solvent directly on top of all six pistons. Lets hope it doesn't come to that.

[Gearbox]

Sounds like a plan, thank you for the advice, I'll let you know how it turns out, Allan

[Gearbox]

Thanks Ed, that did the trick. Opened the side panel, took a small adjustable and rocked the pistons back and forth. Really not much, felt like stirring cookie dough at first, then it started to free up in no time. Took more time putting the air filter back in, but she now runs. Thank you, now to puts some miles on the car, Cheers Allan