Fuel Pump No Power - Help!

vesnyder · vesnyder's Garage

My fuel pump is not getting any power? I've changed the fuses and the relay at the relay board in the engine compartment and nothing? Any other ideas

John Rogers · 10-02-2005, 07:41 PM

What fuel system is it? Carbs, D-Jet or L-Jet? Did you check power at the hot side of the fuse? Try jumpering the relay so the pump will get power whenever the key is on. If it doesn't run with the jumpers, check power at the relay terminals and at the pump and make sure the pump has a good ground.

Goge · 10-02-2005, 09:57 PM

The one time my 914 left me stranded, was the fuel pump not coming on. After having it towed and checking things out... I unplugged the big connector to the brain to check resistances, etc.

After finding things OK, I cleaned the connections and plugged it back in, a little disappointed not to find anything. On a whim, tried it again, it started right up and has run fine ever since.

My only guess is I had some corrosion across one of those contacts between plug/brain. Worth a try I s'pose!

'72 1.7 is what I gots.

-Todd

vesnyder · vesnyder's Garage

Good suggestions, will give them a try. It stranded me as well and died when I pulled the heat lever up - concidence? I don't think so!

It is a D-Jet (I think - '73).

Stay tuned!

vesnyder · vesnyder's Garage

Trying to figure out why my fuel pump is not getting any power and determined the power for the pump comes directly off the coil. The voltage leaving the relay panel is ~12V, but coming into the coil is only about 2-3V - that is with the wire disconnected - with it connected to the coil it is only ~.3V. Is this right? How do I determine if the coil is bad? How much for a new one?

John Rogers · 10-03-2005, 09:41 AM

If the voltage at the coil terminal is that low then the wire runing to it from the relay board is bad. The coil should have nothing to do with the voltage to the fuel pump. The wire color with the voltage to the coil is black and runs from the relay board through a short harness to the coil connection. It could also be a dirty or bad pin on the relay board too.

swl · 10-04-2005, 03:56 PM

I'm a little confused with the discussion of the coil. My wiring diagram shows the power source to be directly from the battery, through pin T4-14, fuse, relay then out to the fuel pump by way of pin T4-13.

You should see 12v on pin T4-13 (T4 is the 14 pin plug at the front of the relay board) whenever you expect the pump to run - 3 seconds at key on or while cranking. pin 13 is the left most pin on the front row. That's a good point to isolate the search. If 12v isn't there then you have a problem on the relay board. If there is 12v there then it is a straight run to the fuel pump - wire could be broken or contact at pump corroded. You can slide of the cover off the plug to gain access to the pin with everything still connected.

gint · 10-09-2005, 10:58 AM

Quote:

Originally posted by swl
I'm a little confused with the discussion of the coil. My wiring diagram shows the power source to be directly from the battery, through pin T4-14, fuse, relay then out to the fuel pump by way of pin T4-13.

It's a common DPO "fix" when they can't figure out the electrical problem (like you obviously have). They wire the fuel pump to the coil to get 12v. I've bought at least one 914 like that (and later fixed it), and I've heard of plenty others.

And no, it's not the right way to do it.

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Brad Anders has a flowchart for diagnosing fuel pump power problems on his incredible Website of All D-jet Knowledge.

http://members.rennlist.com/pbanders

Bill Williams wrote up a text article for troubleshooting the fuel pump system as well. The article is available on Tim Jones' 914 Fan Page.
http://www.914fan.net/fuelpump.html

--DD

swl · 10-10-2005, 06:58 AM

Quote:

Originally posted by gint
It's a common DPO "fix" when they can't figure out the electrical problem (like you obviously have). They wire the fuel pump to the coil to get 12v. I've bought at least one 914 like that (and later fixed it), and I've heard of plenty others.

And no, it's not the right way to do it.

Ah. Now I understand. So that may explain the corelation with the heater. The relay for the heater fan is fed from the same source as the coil. It it were me I'd pull the heater relay and try the voltage measurements at the coil again. And I'd also restore the fuel pump to the fuel pump relay where herr doctor intended it. But then again I like taking on lost causes.