So I think I need a little advice from everyone on here with a bit more experience with these things than I have.
I've read info from Rennlist:
http://www.rennlist.com/techarticles/djetronicfuel.htm
and from Bowlsby.net:
http://bowlsby.net/914/Classic/TechNotebook.htm

In the last couple of years, I've driven my 914 infrequently, and I have had an ongoing issue with fuel pumps failing. I am now about to order my fourth fuel pump, and I am quite upset about throwing so much money at a problem that really seems like it should be fixed.

After my last repair (installation of yet another fuel pump) there was a strong fuel smell in the garage. I realized that almost all the hose clamps on the fuel lines under the car (around the fuel pump) were loose and fuel was draining out white rapidly. I fixed this issue and the car seemed to be running great. A few weeks ago I went to start her up and drive away, and by the end of the block I was feeling the typical 'ch-chug-a-chug' for the car dying from fuel starvation. HELP!

I'm determined to tackle this on my own this time, and this is what I have found:

1) Wiring to the pump seems a little brittle, but it appears to be functioning. Turning the key to on before hitting the starter produces 12V at the fuel pump wiring for less than a second. This seems to be working properly, please let me know if this is not correct!

2) Fuel pump will not respond to jumping from a motorcycle batter (12V) so I am assuming it is dead and will order a new rebuilt one. Since I have had two rebuilt fuel pumps from the same place (not a 914 specialist) I was going to order all my parts, including the pump from AutoAtlanta, unless someone recommends something else?
It appears that my previous pump rebuilder sprays the entire pump with black enamel, including the hose nipples. That means dissolved paint is going into my engine! Not bad in small quantities, but flakes could clog the lines...


3) The hoses going from my Air Cleaner up front to my charcoal cannister are broken. Could this contribute to a lack of air in the gas tank to replace fuel as it is pumped out, therefore putting higher strain on the fuel pump and potentially burning it out?
Pic of my hose:


4) My gas tank and sock appear to be relatively clean. there are some small particles, which I might try sopping up with towels in the tank, but it does not appear to need treatment, or even a new sock?


5) Where the hose from the charcoal canister attached into the gas tank filler neck, the fitting appears pinched, but air does appear to flow through it. Is this normal?


6) This is a picture of my fuel filter. This does NOT appear to be the correct filter for a 914? one side is a 8mm and the other is 12mm?!?! You will also note the ARROW showing flow direction points from the 8mm to the 12mm?!?! It was installed on my car in the OPPOSITE direction that the flow arrow shows, with the 12mm side connected to the supply from the tank and the 8mm side connecting to the S on my fuel pump. This to me seems like it might be the primary culprit? Could reversing a fuel filter be that bad?


7) My under the car heater hose is cracked/broken out of place. It is quite possible that hot air was being blown on my fuel pump? This seems like a BIG no-no, but if this was the culprit, I would expect my fuel pump to have failed in the middle of a long drive on a hot day, not on a freezing morning when I am just leaving the driveway? This should be fixed either way.

8) Since I have a 12mm line and a 8mm line at my pump/filter, I am a bit confused, and potentially worried about the hoses hooked up in the wrong order to my fuel pump. The image I found from bowlsby.net was quite helpful:
http://bowlsby.net/914/Classic/zTN_FI_Hose...ump_1970-74.jpg
but it makes me think I am missing #6, the 9mm to 7mm reducing hose. Then I realize I don't even have a 10mm or 9mm, but a huge 12mm. Could my lines be misconnected?
I took this shot of the R-Return line coming from the pump, going to the Y and then it is clipped into the side of the body. Anyone have any idea if this is correct or if this should in fact be my S line? (terrible picture, my apologies!) Perhaps someone could post up a picture of the 9mm to 7mm adapter?


If anyone has the patience to read over any of this, I would be extremely appreciative. I feel like I'm shooting in the dark a bit, with no clear idea of what is destroying these pumps.
Cheers,
Orange71

Sorry about your problems In response to your questions, the only one I can answer at this time is the charcoal canister question: I think the frayed hoses have nothing to do with venting the gas tank. You could assemble your fuel system to "factory" specs (ie, fuel filter direction) and go from there. When I'm in the garage today, I'll measure the port sizes on the fuel filter. When I had my car in for a tech inspection, the shop mechanic advised me to use a BMW all-metal canister filter instead of the plastic one.

Okay a few things...

-It sounds like you're getting power to the pump so that shouldn't be your problem.

-The charcoal canister being hooked up should not affect your running condition.

-If you haven't already, make sure all fuel lines are in good condition or replaced.

-Your fuel filter is not the correct one for a pre-75 system. Fuel flow should point in the direction of arrow. Stock filters were 8mm on both ends which was also used with the reducing hose (9mm to 7mm) shown in the diagram you posted. I would get a correct fuel filter and line from AA if you order from them.

-You said your supply line coming from the tunnel line to the filter was 12mm? That's definitely not correct. It should be the 9mm to 7mm reduction hose.

-If you think paint flakes got into you engine, you might have clogged injectors too. I would check/clean them to be sure.

-Your tank looks fairly clean. I would try to get some of that small debris up. Is that a penny in there?

-This fuel diagram might also be helpful

Click to view attachment


Good luck and keep us updated.

what year is it? that is the correct fuel filter for a 75-76.

76-914:
It is a 1971 1.7L D-Jetronic.
I looked up the part numbers and it does look like that is the correct fuel filter for a 75-76, but it still appears it was installed in a reverse flow direction?

dlee6204:
- All fuel lines were replaced a few years ago, when I first got the car back on the road. This work was not done by me, hence my confusion!

- I will be ordering the 8mm/8mm filter and the reducing hose.

- That diagram is most helpful. I'll get my calipers on the flexible plastic fuel line and check their diameter. If I can confirm that the flexible plastic lines are the right sizes it will both confirm the S/D lines to the pump and alert me to how much line I need to replace to take care of the 12mm line.

- I thought it might be a penny as well. Too bad my magnetic extender doesn't pick up coins!!!

type47:
I am actually running the metal charcoal canister, but the car probably has more than 200k on it, so that charcoal expired a long long time ago!

The previous owner described what sounded like occasional vapor lock when the tank is very very full. I have never experienced this, but it does make me wonder about the venting on the tank, hence my questions about the air hose/charcoal canister. Could anyone confirm that the pinched nipple in picture #5 is typical for the air hose to filler neck? That's my main outstanding unknown right now, even if it doesn't affect my pump...

Thanks for all the replies!

Just came up from the garage and from checking my flexible plastic fuel lines.
I have got one 7.6mm OD and one 9.6mm OD line coming from the tank towards the fuel pump, so it is quite clear which is S and R. Looks like they have been correctly hooked up and the Y is in the right place.

I'm hoping the .6mm OD difference is small enough that I'll still be able to hook up the 9mm to 7mm reducer.

About to pull the trigger on the order. Will post up once the parts are in place, with fingers crossed that the pump will survive!

The pinched nipple in the filler neck is normal.