Fuel relay - pump question..........help!!

[schubee]

Here’s my problem. After Monday’s event at the Street’s of Willow, my car ran excellent until Tuesday afternoon. Luckily I was home when my car wouldn’t start. It cranks over fine but it just wouldn’t start. I noticed I didn’t hear my fuel pump turn on before I cranked it over. So, I checked my fuses and everything is okay. I wasn’t sure how to check the relay so here’s what I did. I found out there’s no power to the fuel pump. I hooked up a 12 volt to the pump and that worked fine. I then swapped a relay and still no avail. However, when I hooked the fuel pump relay to the power windows, it worked fine. Now here’s my question, would the fuel pump relay work for the power windows but not give enough circuitry to my pump? I’m not really sure how I can tell if it’s the relay or something else. I guess I’ll spend the $20 for a new one and have a spare if it’s not the problem…..any ideas? Thanks in advance for your comments.

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John
'81SC Targa

[wckrause]

Did you check the fuse?

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Bill Krause
'79 911SC Euro
MY PELICAN GALLERY

[Britwrench]

Lets get some info first..what year is your 911

It could be the fuel safety switch on the air flow sensor..pull the connector off and
with the ignition on (engine not running) the pump should run.

If the relay works the windows it's ok.
Could also be a wiring fault at the relay connector.

[schubee]

Bill: Yes, I checked the fuse. It was fine but I still replaced it with a brand new one.

Britwrench: It's an '81 (look at my sig). Fuel safety switch on the air flow sensor?....didn't know I had one. I'll check it.




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John
'81SC Targa

[john walker's workshop]

the fuse block terminals on either side of the fuel pump relay get burnt black and the wires often don't look too good either. the fuse is before the relay.

[Doug Zielke]

Originally posted by john walker's workshop:
the fuse block terminals on either side of the fuel pump relay get burnt black and the wires often don't look too good either. the fuse is before the relay.

Listen to John W. and check this out very carefully.
The Blue Bomber just burnt up her fuel pump fuse holder over the weekend. Could have been nasty, but she made it back to the garage in time.
(And thanks John...I got her all fixed up. Damn those screwball German fuse holders. Are they Hitlers payback??)



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'81 SC Coupe (aka: "Blue Bomber")
Canada West Region PCA
The Blue Bomber's Website
"If it ain't broke...we'll help you fix it 'til it is!"

[schubee]

Alright, I purchased a new relay and that wasn't the problem. Now I'll check what JW and Doug suggested. However, I'm still confused on what fuse on either side of the relay to check? Am I missing something here? On the fuse box cover, it does indicate that the 6th fuse is for the fuel pump. I replaced it but now I found that there are no wires even hooked or connected to that block. I am more confused and getting frustrated and tired. I need some sleep and I'll tackle this again tomorrow. Thanks again for the help!

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John
'81SC Targa

[garrickl]

Look at Lee Rice's article in the 911 Tech section regarding electrical upgrades to your fuse panel. My 930 has two fuel pumps. The front started making noise so I replaced both front and rear. My relays were also very hot. I did what Lee suggested and broke off the AC and fuel pumps and alarm into separate circuits ...... what a difference. The AC works superbly, the fuse box is cool, my door lock selenoids feel like they are brand new .... bottom line is your system may be starving for electrical power like mine. Look at the fuse panel and see if any of the gangs appear "burnt" or discolored .... if so, replace them. I may have replaced two fuel pumps ($600) unnecessarily when all they needed was a solid steady supply of juice.

[john walker's workshop]

sorry, i meant to say check the fuse block terminals on either side of the FUSE. the 6th fuse from the windshield forward. there should be a red wire off the bottom that powers the relay at terminal 87A. pump power off the relay is terminal 30, which also powers the warmup regulator and air regulator.

[schubee]

JW, I apologize for my ignorance on this issue. You mentioned terminal 87A and 30. I would like to check these however I don't have a clue where they are. Furthermore, I haven't checked my fuel safety switch on the airflow sensor like Britwrench suggested. Does my car have this safety switch?....if so, where is it located?

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John
'81SC Targa

[john walker's workshop]

pull out the relay and on the pin side, you will see numbers next to each pin. the sensor plate contact(emergency fuel pump cutoff switch), is on the sensor plate housing behind the rubber boot that's on top of the housing. a green plug. you can reach it with your left arm coming in from the driver's side of the intake area.they usually are not a problem.

[This message has been edited by john walker's workshop (edited 10-11-2001).]

[Early_S_Man]

schubee,

The Parts and Technical Reference Catalog has pinouts of all the common relays, but JW is right in that most have pins and schematic on the package.

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Warren Hall
1973 911S Targa
1992 Dodge Dakota 5.2 4X4 parts hauler

[schubee]

Thanks everyone. I finally found the problem. I found that the relay was not getting any power. So I ran a lead from circuit 87A to a fuse block and wham, the fuel pump turned on. Since there were no wires to the fuel pump fuse block, I found out that the idiot whoever worked on it re-wired the fuel pump and had a different fuse outside of the fuse box. So, my problem only consisted of one damn fuse. After 3 days of headaches and sleepless nights, my P is back on the road. I'm also sporting an extra relay! Thanks again!

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John
'81SC Targa