Fuel pump issues, no power to pump Options

[Tab914]

Hello all,

Well took the teener out today to start my summer driving. Charged the battery and car started on first cranks. Let the car run for a bit, turned it off and turned it back on. Pulled out of the garage and took pictures to get a new insurance policy and let the car sit for half an hour.

Here is where the fun begins. Go to start the car to put it back in the garage and......nothing. Don't hear the fuel pump buzz when I turn the key. Push the car back in the garage and start testing.

The car is a 1974, 2.0lt d-jet.

Direct power to the pump shows that pump works.
Jumping the relay shows that power from the relay board will reach pump.
When pump is running while jumping the relay, the car cranks but won't start.
Then, when checking the main power relay, looks like I am getting no power to the relay board.
Swaped out the computer (brain) for another and still no power to the relay board.
Tried jumping the wires at the relay under the passenger seat and still nothing.


Been going over and over the electrical diagrams and getting nowhere.
Got tired and can't think anymore.

Very frustrating after having the car start right off the first crank.

Is there something simple I am not thinking of?

Thanks in advance to whoever can help. Appreciate all answers / suggestions.

Will check tomorrow after a nights sleep.

Cheers,
Dominic. (IMG:style_emoticons/default/beer3.gif)

[SirAndy]

try swapping the relay for one of the headlight relays ....

they *do* go bad every once in a while ...
(IMG:style_emoticons/default/shades.gif) Andy

[ejm]

Then, when checking the main power relay, looks like I am getting no power to the relay board.

This power comes to the board thru one of the red wires at the batterys positive post. Check the connections there.

[Tab914]

Hey Andy,

Thansk for the reply. I tried that first thing though and with a few relays and still nothing.

The problem is that I'm getting no power to the relay board and wasn't sure where the power came from.

ejm,

I will check the red wires and their connection after work. I have 2 wires coming from the post. Does that sound right ?

Will let you know what comes of it.

Thanks for the reply ejm.

[ericread]

A couple of ideas:
1. Are you sure the fuel pump is OK? How about running a couple of wires directly from the battery to the fuel pump to see if it runs. Once you have proven the fuel pump is good, then it's time to start tracing your wires.

2. Ground problem? Make sure your grounds are very, very good.

Hope this helps (IMG:style_emoticons/default/confused24.gif)

[Dave_Darling]

A couple of resources for you--

Text troubleshooting article:
http://web.archive.org/web/20050218100647/...t/fuelpump.html

Flowcharts for troubleshooting:
http://members.rennlist.com/pbanders/FPChecklist.htm

--DD

[Tab914]

Hey Eric,

Did that as well and that did show me that the pump works for sure. Also jumped the relay with a wire and that got the pump buzzing as well. Grounds are good.

At the moment I'm pretty sure it's a power to the relay board issue.

Thanks for your help

Dominic. (IMG:style_emoticons/default/beer.gif)

[Tab914]

Dave,

Wow.

A lot of info in there.

Haven't gone over it all as I am at work but anxious to read through it. I am sure that will help.

Thanks alot,

Cheers, (IMG:style_emoticons/default/beer3.gif)

Dominic.

[dbgriffith75]

At the moment I'm pretty sure it's a power to the relay board issue.

Okay, I'm not 100% sure on where all power feeds into the relay board from, but I have to ask: is the fuel pump the *only* thing not working when the key is turned on? Do other devices that run off the board get power, such as the motor blower, coil, and alternator? (Okay I know the alternator doesn't "run" off the board, but there's a harness that runs between it and the board.)

I'd check to see if you're getting power to these as well, because if you are, it might be that you've got a bad circuit in the board itself. Or there's just a bad ground that you're not finding. You might also want to check your voltage regulator- if its bad, it might be cutting off power to the pump. Just a thought, but I don't know for sure that the circuit runs through the regulator.

Just a few things to check out.

[wertygrog]

hmm...my fuel pump stopped working a few days ago...after getting a tow home (from my dad's jeep lol), it just turned out that one of the two fuses on the relay board had its contacts corroded, and was only allowing 4V to get to the pump. So I'd check that if I were you..also check the contact poles on the relays..... (IMG:style_emoticons/default/idea.gif)

[ericread]

WOW! Dave Darling's stuff is amazing!!! (IMG:style_emoticons/default/smilie_pokal.gif) Let us know how your troubleshooting (using the flowchart) goes.

Eric

[Dave_Darling]

You mean Bill Williams' article, and the amazing Brad Anders' flowcharts, right? (IMG:style_emoticons/default/wink.gif)

--DD

[Tab914]

Well the flow charts are great. From isolating the problems to the right steps to troubleshoot them.

Got the car running again after doing the following.

Checked and cleaned connections of red wires running from the + battery pole.

Using the charts I established that I was in fact getting power to the relay board. (good)
After pulling the plug on the board (the one closest to the firewall) I found a bit of corrosion there so cleaned that off while I was at it.
After following the charts and doing the tests I found that I wasn't getting any ground to the fuel pump relay (relay 75) and that that is why it wasn't working.
Looking at the trace on the relay board for that ground I found that it went back to the five wire plug at the back of the board marked with roman #s I - II - III and IV on the relay board chart and that it trace to the pin marked III
These wires go back to the ECU. After pulling the ECU and checking continuity in the wires I found everything to be OK there. Reconnected the ECU, checked its ground at the back of the engine along with the injector grounds and made sure those were clean and tight.
Cleaned the connection at the plug marked with the roman #s and I think that that is were my problem came from. Bad ground connection at pin marked III was preventing relay #75 (fuel pump relay) from working.
If I look at the relay board chart properly it looks like relay #75 is the only relay that grounds at that point. (must be a reason) Anyway........

Put that plug back in and car started on first crank.


All of this to say that it was a grounding problem between the board and the ECU. Took a while to figure out but lucky that all components work.

Needless to say that those charts worked wonders. Couldn't have done it without them.

Hope this and the chart will help others and save some time finding the problem.

Thanks to Dave Darling, Eric Read, EJM, Sir Andy and Brent D. for all your help and suggestions.

Cheers everyone (IMG:style_emoticons/default/beerchug.gif)

Dominic.

[ericread]

Glad to hear you're mobile again! (IMG:style_emoticons/default/driving.gif)

Eric

[swl]

Dominic,
Pin III is not exactly a ground point. The ecu switches that to ground when it wants to run the fuel pump. It only runs the fuel pump for the first half second then not again until the engine is turning over. You can hear that when you first turn the key on - a quick buzz from the fuel pump then it shuts off till you hit the starter.

[Tab914]

Thanks Steve.

Good to see a fellow canuck replying. We're only a couple of hours away from each other.

Well my problem came back again today. Have to go through the whole process again. 99.9% certain that it's a grounding issue but just need to find out where !!! Seems like it's intermitent so must be a bad connection somewhere or a bad trace on the relay board.

Just put my new Ontario plates on today. Started the car, let it run and it just stopped on its own and again no power to the pump. Strange.

More time in the garage I guess.

%@#@&*!!@

[roadster fan]

Well, I had this same problem on my 71 a while back. Pump stopped working, went thru all the trouble shooting stuff, cleaned and the connections, worked great....................for about 3 miles then died about 1/4 mile from my house.

I narrowed the problem down to the same ECU circuit that connnects on the relay board at pin III also. Swapped the ECU for another after determining all the wiring was good and reading Brad Anders' info about how the circuit works on the ECU.

Fuel pump circuit worked for 2 days and then crapped out again. I opened up the first ECU and started tracing the fuel pump circuit on the board and found a transistor that had three corroded legs and one was broken. I will take pictures and post later. I am trying to source a replacement transistor as the broken leg appears to be the cause of the intermittent problem. It doesnt totally fail, but due to vibration will fail, then if you unmount the ECU and check the cables it will make a connection and you think you fixed the problem only to have it happen again after you run the car for a while.

Frustrating problem so I bypassed the ECU fuel pump circuit, and have the pump run whenever the ignition is on. I ran a wire from pin III to the ground point near the relay board below the drivers side sail. I used a small screwdriver to remove the spade terminal in the white plug from the ECU. I will post a pick of this as well. This works good, I know some will say that if the car is involved in an accident and the engine stops that the pump will continue to pump fuel creating a fire hazard but really you just need to shut the ignition off to stop the pump. When I find the replacement part I will fix the two ECU's and go back to the stock setup. When you see the picks of the transistor you will see why and how they fail.

Whew, sorry for the long post but I hope it helps you with your problem. Photos to follow in a little while.

Jim

[roadster fan]

The following pics are of the 015 ecu and relay board in my 1971 1.7. The fuel pump circuit will differ a little on the other version ecu's but i suspect that the culprit will still be the transistor shown here. It may be in a different location the board, but can be located by following the Cable pin trace on the board as i did and looking for obvious problems with the components on the board.

The T401 transistor on the 015 board did not stand up to the "wiggle" test and one of the legs was apparently broken. I began to look more closely at the component and the transistor came of the board leaving the bottom of the "legs" still soldered to the board. This was with almost no force at all. Closer inspection revealed the legs were heavily corroded.

The transistor was mounted with the three legged clear spacer underneath keeping the three pins or legs of the transistor seperated. The round foam insulator(?) was next, with the three pins poking thru it. This is where all the corrosion was and I believe it was caused by this piece of foam. The Electical Engineers here will have to advise what he foam is for. The other piece pictured was epoxied around the transistor body and I believe is a heat sink.

[roadster fan]

Oh, forgot the transistor pic





and the pic of the relay board modification



Hope this helps,

Jim

[swl]

Intermittent can be a beast. If you can catch it in failure mode then you stand a chance.

Another thought is the fuse. I've had it and one other guy on the board had it. Exactly as you described - driving along minding my own business and it suddenly stopped. Poked around for a while and off it went. For me it was the fuse itself where the filament attaches to the cap. For the other guy it was actually the pcb where the fuse holder connects. If you can catch it in failed mode check the voltage on both sides of the fuse - should be the same.

I have a known good relay board I can loan you for troubleshooting if worse comes to worse.

PM me if you want someone to kibitz in real time this weekend over msn or similar.