Hey, We started the engine today for the first time. We put lubricant in the cylinders and it sit for about three days, turning it over periodically. We added fuel to the tank, after pulling the sending unit, to inspect for rust. The pump inder the front of the car is getting fuel to the injector pump, but the car wont run, except from gas poured into the intake(s), which using this method, runs fine. Does the injector pump need to be primed? Thanks

 

Is the belt between the left camshaft and MFI pump intact?

Pete

 

Yes, its appears to be fine. Does the pump need to be primed? The car set for quite awhile.

 

I had simular problem getting my 73 mfi to go after a long sit....turned out the throttle lever beside the brake handle was not working. The dealer told me to press the pedal to the floor, then start to cranck, then after the car cranked for 2-3 seconds leave my foot off the gas pedal quickly.. it worked the car started. and this is how i start it with my broken throttle adjustment. its is hard starting this way but always startes after a few trys. another silly question... do you have spark?

 

Yes! The car runs smooth on gas poured into the the velocity stacks. Once primed, cranked for a few seconds, the engine hits and idles for a few more seconds, then dies. Its a fuel delivery problem, I am just not too educated on this kind of injection. I am a 10 year BMW man...but a porsche infant

 

I have read info after info on the system.. their really is not much to it but it absolutly HAS to be right. especially all the linkages. but if it ran when you put it away i wold say they should be close enogh to at least run.. another problem i had that made a WORLD of diff was the plugs. I put in the recommended MFI plugs ($12/ea) some people said i was nuts but it made things better. The MFI pump is to be REALLY reliable. My guy that has been working on 911's here told me he has never replced one. So i really doubt its the pump.. what about the injector nozzles? they are just a nozzle not an actual valve like whats on late model cars. the hole in the nozzle is very small to almost vaporize the fuel as it enters the cylinder,, maybe as it sat they got clogged.. i replaced all of mine. also ( i don't know if it needed it, but i did it. I figured after sitting for a year they were clogged) I think nozzles..... do you know the history about the car? why was it let sit? A lot of times you can learn a lot by looking at the cars past.

 

I just bought the car within this last week, it was told the previous ovner was driving it, and it just died, he thought it was the fuel filter. We have found fuel all the way to the injector pump, and it stops there. Removed the supply line to one of the front injectors, and its not getting fuel to it. It looks like the fuel is stopping at the injector pump. Which means the fuel is getting past the filter. The injectors wont matter if nothings getting to them. TOmmorrow I will try the method you mentioned earlier.

 

I see, you have done your home work.... I have some really good info do you want me to email it to you? whats the address?

 

Sure, Any info is good. I have learned some things, but like I say, I am new to porsche. this is my third, my first was a '69 912.. RUSTY! Got it gone. My second was just a rolling chassis, a 1964 356c... I basically bought it for resale, but I want to keep this one. It is rusty, but other than rockers,the rest is mostly surface rust. My email is rsellers@highland.net

Thanks!

 

Lex: It's possible that your fuel pump is working, but not delivering the volume required by the MFI system. There is a spec in the manual for delivery quantity, have you checked that? You have a tricky symptom, you might want to consult a local tech on this one, especially if your delivery is OK. I have seen, twice in my career, where an MFI car would not run, because it only had three cylinders due to a timing chain failure of some sort. Those cars would run a bit with priming, but would not start the ordinary way. I hope that this is not the case with your car!
Pete

 

We are thinking fuel pump also. The car runs good on pouring gas into the intake(s). Plus all cylinders have compression so I would say thats not the case. There is fuel getting to the injector pump, but we think its not enough, and the pump is now sprouted a leak, and its getting to a point where you have to "peck" it with something to get it to kick in.I know it looks like the pump is bad, because of the "banging" thing, but when running it puts gas all the way to the injector pump, and stops. How much pressure should it be putting out?..

 

By the way, what manual are your referring to, I need a good one. How much is a new pump?

 

I do not think youare going to find a new pump. but from what i understand they can be rebuilt. this little article gives you a name of a place that will do that.. I just got a new computer here at the house and i forget my outgoing mail server name...... but you know what i have a yahoo acct i will send it from there. it is an article someone sent me off a board it is by Leslie rice. I think it came off this board. ALSO FYI this board has been invaluable with my 928 and 911.... you really should think about joining. I will send the doc today

 

it never ends... i have a hard copy but can not find the PDF to send you...... i will look for the PDF again later after the kids go to bed tonight or if i am lucky enought for them both to nap at the same time.

 

Thank, I appreciate any help I can get. The pump I was refering to is the delivery pump, under the car. I am thinking its not up to specs. and the MPI pump is not getting the fuel it needs. I think its getting just emough to make me thinks its working.

Am I right in assuming the MPI pump operates from the pressure and volume of the under front delivery pump?.. The cam belt drivers it, but the without proper pressure/volume coming into it, it will look like the MPI pump isnt functioning correctly?

I dont think the MPI pump is bad. The car was parked because it just died, the guy was driving it and the engine died..and wouldnt start back, MPI pumps wear out or get gummed up. This pump is clean. How much oil should be circulating in the MPI pump?