 FI fuel and wiring routing |
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| watsonrx13 |
 Jul 21 2008, 06:20 AM
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#1
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Advanced Member  Group: Members Posts: 2,734 Joined: 18-February 03 From: Plant City, FL Member No.: 312 Region Association: South East States  |
I've put my engine back in the car and want to confirm the FI fuel routing. I've looked at PP/Dave Darling's diagrams, but would like confirmation:
 1. large (9mm) plastic fuel line from firewall connected to fuel filter 2. fuel filter connected to fuel pump at (S-suction) connection 3. (D-damper) connection on fuel pump connected to fuel rail on passenger side, rear connection 4. (R-return) connecton on fuel pump to Y connection 5. Y connection to small (7mm) plastic fuel line from firewall 6. Y connection to fuel pressure regulator 7. fuel rail on passenger side, front connection, to fuel rail on driver side, front connection 8. fuel rail on driver side, rear connection, to fuel pressure regulator 9. fuel rail on driver side, middle connection, to cold start valve. Also, I'd like confirmation on the electrical connection to the fuel pump: 1. black/red wire to the + side of fuel pump 2. brown wire to the - side of the fuel pump If I wanted to test the fuel pump outside of the car, I should be able to connect a positive wire to the + of the fuel pump, then to the + side of a battery, then - fuel pump to - battery. I could then connect the (S) fuel line and place in a container of gasoline. Then place the (D) and (-R-) fuel lines into an empty container. When I connect up the electrical lines, I should get the pump to hum and run fuel through the pump. Also, if I turn on the ignition, I should be able to get voltage across the black/red wire and the brown wire, correct? Finally, has anyone successfully found a shop that can rebuild these fuel pumps? -- Rob |
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Replies(1 - 19)
| swl |
Jul 21 2008, 08:06 PM
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#2
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Senior Member Group: Members Posts: 1,409 Joined: 7-August 05 From: Kingston,On,Canada Member No.: 4,550 Region Association: Canada |
Daves drawing is right on from all accounts. Assuming of course we are talking about a 2 liter. Rest of the assumptions look good to me except:
Power across the fuel pump is only applied for 1.5(ish) seconds after key on then not again until the starter is engaged or the engine is running. To get constant power ground pin 3 on the 4 pin connector on the relay board. Probably a good idea to connect the return line from the pump to your output container in your out of car test rig. You can get bypass fuel coming out there particularly with air in the system. These pumps don't pump air well so you might want to get the pump below the gas container and give it a little manual prime. I haven't found a rebuild source. No rebuild kits either. You do see rebuilt pumps for sale but where they source the rubber parts from seems to be an industry secret. |
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| watsonrx13 |
Jul 22 2008, 06:28 AM
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#3
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Advanced Member Group: Members Posts: 2,734 Joined: 18-February 03 From: Plant City, FL Member No.: 312 Region Association: South East States |
Steve, thanks for the reply. I forgot to add that yes I'm working with a '74 2.0l engine. Earlier this year I bought a FI fuel pump that supposedly worked. When I installed it and added power, I didn't get any humming, so I removed it and connected it directly to a battery, but without any luck. So, I tried another pump, hooked directly to the battery and got a hummer... (IMG:style_emoticons/default/biggrin.gif) . So I connected everything back in the car and turned on the ignition, but no hummer. Since it appears that I'm not getting any power to the pump from the electrical system, I'm going to hot wire it. I'll try jumping the relay, but if that doesn't work, I'm going to run a hot wire (switched) from the fuse panel.
-- Rob |
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| swl |
Jul 22 2008, 06:40 AM
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#4
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Senior Member Group: Members Posts: 1,409 Joined: 7-August 05 From: Kingston,On,Canada Member No.: 4,550 Region Association: Canada |
I'm not a fan of hot wiring Rob. The relay board looks a little daunting but it is relatively easy to troubleshoot and fix. Most of the time it is a relay or the fuse. I've also heard of the fuse holder needing to be fixed. If you spend an hour trouble shooting there you should be able to find the source of your problem. Be happy to talk you through it. A cheap multimeter is all you need.
There was thread recently about a fuel pump that would not spin. Turned out to be stuck brushes. It would be interesting to see if that is the problem with your pump that wont hum. |
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| watsonrx13 |
Jul 22 2008, 06:56 AM
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#5
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Advanced Member Group: Members Posts: 2,734 Joined: 18-February 03 From: Plant City, FL Member No.: 312 Region Association: South East States |
Steve, thanks... I do have a multimeter, but I'm a little electrical-challenged... (IMG:style_emoticons/default/biggrin.gif) I'm currently at work, but any recommendations and/or steps you can give me to trouble shoot my electrical problems would be great. I've already swapped the relay with another known good one, but still no go. This past weekend I had a friend come by and while he turned the ignition on, I had the multimeter across the leads, but only registered 0.03 volts.
Also, how do I check the brushes in the motor? -- Rob |
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| SirAndy |
Jul 22 2008, 12:20 PM
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#6
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Resident German Group: Admin Posts: 41,676 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
QUOTE(watsonrx13 @ Jul 22 2008, 04:28 AM)  So I connected everything back in the car and turned on the ignition, but no hummer. in order for the pump to work correctly, the FI brain must be hooked up and plugged into the relay board! and you also need the pump relay in the board and the the fuse on the board. (IMG:style_emoticons/default/bye1.gif) Andy |
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| watsonrx13 |
Jul 22 2008, 07:20 PM
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#7
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Advanced Member Group: Members Posts: 2,734 Joined: 18-February 03 From: Plant City, FL Member No.: 312 Region Association: South East States |
QUOTE(SirAndy @ Jul 22 2008, 01:20 PM) QUOTE(watsonrx13 @ Jul 22 2008, 04:28 AM) So I connected everything back in the car and turned on the ignition, but no hummer. in order for the pump to work correctly, the FI brain must be hooked up and plugged into the relay board! DONE and you also need the pump relay in the board and the the fuse on the board. AND DONE (IMG:style_emoticons/default/bye1.gif) Andy Next, suggestion.... (IMG:style_emoticons/default/smile.gif) -- Rob |
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| Cap'n Krusty |
Jul 22 2008, 07:38 PM
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#8
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Cap'n Krusty Group: Members Posts: 10,794 Joined: 24-June 04 From: Santa Maria, CA Member No.: 2,246 Region Association: Central California |
The hose from the plastic supply line to the filter is 7mm on one end, 9mm on the other. The part number is 914 356 525 00, and it's readily available from your local Porsche dealer, although they may have to order it. Around 25 bucks.
DO NOT "make something fit". Fire's an ugly thing and, odds are, you'll have one if you cheap out on the job. The Cap'n |
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| swl |
Jul 22 2008, 10:09 PM
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#9
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Senior Member Group: Members Posts: 1,409 Joined: 7-August 05 From: Kingston,On,Canada Member No.: 4,550 Region Association: Canada |
Tab914 was the guy who discovered the brushes problem. I'm on the road and the hotel gateway is really fracking with my browser - can't give you a direct link but the thread is called 'fuel pump issues, no power to pump'
I've been searching for the thread with the relay board diagram but am getting frustrated by this browser thing. So I'll try from memory (dangerous!) 1 lift the power to your coil during testing to guard against welding your points. 2. key on 3. with volt meter measure from ground to each side of the fuse. Should be 12-13V on both sides. 4. if power to the fuse is good then uplug the 4 pin connector on the back left of the relay board. Use a jumper to ground pin 3 on the relay board to ground. This should turn on the pump but most likely won't 5 if the jumper failed to start the pump then we are probably looking at one of the two relays - main power or fuel pump. replace both with known good relays (headlight motors are a good source). If none of that points to the problem then I need my diagram to take your farther. Background. The main power relay turns on with switched power from the key. It then provides power to the solenoid of the fuel pump relay. The ecu then turns on a 'switch' to ground to activate that solenoid. When the solenoid makes it switches power that comes from the battery through the fuse, through the relay contacts and onward to the pump. Jumping pin 3 is basicly doing the job that the ECU does. |
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| SirAndy |
Jul 22 2008, 11:03 PM
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#10
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Resident German Group: Admin Posts: 41,676 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
QUOTE(watsonrx13 @ Jul 22 2008, 05:20 PM) Next, suggestion.... (IMG:style_emoticons/default/smile.gif) so, did you switch relays to make sure it's working? (IMG:style_emoticons/default/poke.gif) also, a voltmeter is your friend. is the ground wire to the pump working? (IMG:style_emoticons/default/idea.gif) Andy |
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| roadster fan |
Jul 23 2008, 02:05 AM
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#11
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Project Frankenstein !!!!!!!! Group: Members Posts: 1,009 Joined: 24-November 05 From: Aptos, CA Member No.: 5,184 Region Association: Northern California |
Here is the thread that swl is talking about Fuel Pump No Power
I had a problem with my ECU and those pics are in the above thread. Jim |
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| watsonrx13 |
Jul 23 2008, 06:03 AM
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#12
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Advanced Member Group: Members Posts: 2,734 Joined: 18-February 03 From: Plant City, FL Member No.: 312 Region Association: South East States |
Jim, thanks for the link, evidently I missed it originally. (IMG:style_emoticons/default/aktion035.gif)
Andy, I'll use the flow chart and other references to check the fuel pump circuit. If I have all of the circuits working correctly, I'll disassemble the fuel pump and check the brushes. Thanks again everyone... (IMG:style_emoticons/default/drunk.gif) -- Rob |
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| watsonrx13 |
Jul 23 2008, 04:02 PM
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#13
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Advanced Member Group: Members Posts: 2,734 Joined: 18-February 03 From: Plant City, FL Member No.: 312 Region Association: South East States |
Well, I read the postings and noticed that TAB914 (Dominic) disassembled the fuel pump. I was able to remove the (4) bolts on the top and remove that, but how do you remove the motor for the pump housing?
-- Rob |
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| swl |
Jul 23 2008, 06:17 PM
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#14
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Senior Member Group: Members Posts: 1,409 Joined: 7-August 05 From: Kingston,On,Canada Member No.: 4,550 Region Association: Canada |
try pm'ing/emailing dominic - I don't think he is on regularly.
Any luck with the relay board? |
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| watsonrx13 |
Jul 23 2008, 06:26 PM
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#15
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Advanced Member Group: Members Posts: 2,734 Joined: 18-February 03 From: Plant City, FL Member No.: 312 Region Association: South East States |
Not yet, unfortunately life has gotten in the way during the week... (IMG:style_emoticons/default/wink.gif) I'm definately going to work on the car this weekend.... I'll send Dominic a PM to see if he can answer my question.
-- Rob |
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| swl |
Jul 23 2008, 06:49 PM
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#16
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Senior Member Group: Members Posts: 1,409 Joined: 7-August 05 From: Kingston,On,Canada Member No.: 4,550 Region Association: Canada |
QUOTE(watsonrx13 @ Jul 23 2008, 04:26 PM) Not yet, unfortunately life has gotten in the way during the week... (IMG:style_emoticons/default/wink.gif) I'm definately going to work on the car this weekend Me too - but substitute year for week (IMG:style_emoticons/default/smile.gif) Had the backyard equiv of a hell hole repair. But it is done now and I'm going to get some 'me' time in the garage. |
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| watsonrx13 |
Jul 23 2008, 07:41 PM
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#17
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Advanced Member Group: Members Posts: 2,734 Joined: 18-February 03 From: Plant City, FL Member No.: 312 Region Association: South East States |
QUOTE(swl @ Jul 23 2008, 07:49 PM) QUOTE(watsonrx13 @ Jul 23 2008, 04:26 PM) Not yet, unfortunately life has gotten in the way during the week... (IMG:style_emoticons/default/wink.gif) I'm definately going to work on the car this weekend Me too - but substitute year for week (IMG:style_emoticons/default/smile.gif) Had the backyard equiv of a hell hole repair. But it is done now and I'm going to get some 'me' time in the garage. That's right, you had the deck rebuild.... glad you got it completed.... Now back to the important/fun stuff... (IMG:style_emoticons/default/welder.gif) (IMG:style_emoticons/default/sawzall-smiley.gif) (IMG:style_emoticons/default/driving.gif) -- Rob |
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| watsonrx13 |
Jul 28 2008, 06:10 AM
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#18
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Advanced Member Group: Members Posts: 2,734 Joined: 18-February 03 From: Plant City, FL Member No.: 312 Region Association: South East States |
Well, this weekend I tried to disassemble one of the pumps that aren't working. After spending several hours I was finally able to get the bottom section off, but not until after I tried to shove a small bladed screwdriver through the webbing of my hand, between my thumb and fore finger. It appears that the wiring to the electrical contacts were broken, so I decided to throw it away. BTW, I'll NEVER try to disassemble a pump again... (IMG:style_emoticons/default/dry.gif)
I also found that when I repainted the interior of the engine compartment, I didn't keep the paint off of the ground wire bolt underneath the relay panel. I was following Brad's flow chart and the first thing to check was the main power. Before I cleaned it, I had 0 volts, afterwards I had 6 v. According to Brad, if you don't have 12 v then there's a problem with the relay board and it should have the bottom removed and the connections checked and resoldered. I'm not going down that path. Steve (swl) had another list, but I didn't print it out to check, so that's the next step. Anyway, I thought I'd keep everyone updated.... I'll let you know what the final outcome will be. -- Rob |
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| swl |
Jul 28 2008, 07:37 AM
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#19
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Senior Member Group: Members Posts: 1,409 Joined: 7-August 05 From: Kingston,On,Canada Member No.: 4,550 Region Association: Canada |
6 Volts huh - I guess you're halfway there (IMG:style_emoticons/default/biggrin.gif)
Where is that measured Rob. |
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| watsonrx13 |
Jul 28 2008, 06:29 PM
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#20
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Advanced Member Group: Members Posts: 2,734 Joined: 18-February 03 From: Plant City, FL Member No.: 312 Region Association: South East States |
QUOTE(swl @ Jul 28 2008, 08:37 AM) 6 Volts huh - I guess you're halfway there (IMG:style_emoticons/default/biggrin.gif) Where is that measured Rob. I followed Brad Anders flow chart and the first thing to test was to remove relay 74 and wrap a test wire around pin 87 and plug it back in. Connect a DMM to the test wire and turn on the ignition. With the ignition on, I connected the + side of the DMM to the test wire and the - side of the DMM to the engine. I got 7 v. Also, Steve recommended 'with volt meter measure from ground to each side of the fuse. Should be 12-13V on both sides.' When I connected the + DMM to either side of the the fuses and the - DMM to the engine, I only got 7 v. I'm assuming the fuse you're recommending in the fuse on the relay board. So now the question is, why am I only getting 7v? BTW I bought a brand new Optima battery last week. When I test the battery, I got 12.6 v. -- Rob |
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