 This can't be right?, D-Jet |
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| FlatSix |
 May 21 2011, 08:13 AM
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#1
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English Member  Group: Members Posts: 191 Joined: 14-January 03 From: Poole, England Member No.: 144  |
Background:
Car is 1976, and has not been driven for many years (don't ask). The engine is now a 1.7 from 1970. I have replaced all hoses, fuel lines and fuel pump. Problem: The engine will start, run for a few minutes then stop however when the engine is running the fuel pressure is ZERO! Activating the fuel pump by pressing the relay in the engine compartment with my finger brings the fuel pressure up to 28psi and stalls the engine. The car will NOT then restart. When trying to restart I CANNOT always hear the fuel pump run. The fuel presure is 28psi though. Aim: To get the engine running as it should. |
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| trojanhorsepower |
May 21 2011, 08:26 AM
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#2
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Senior Member Group: Members Posts: 1,031 Joined: 21-September 03 From: Marion, NC Member No.: 1,179 Region Association: None |
Let me forward with " I don't know anything", so my suggestions are worth what you pay for them.
Could an injector or two be sticking open when running? Good luck |
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| Cap'n Krusty |
May 21 2011, 08:28 AM
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#3
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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 |
Right off the bat, where did you tap the fuel system for your gauge?
The Cap'n |
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| FlatSix |
May 21 2011, 08:30 AM
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#4
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English Member Group: Members Posts: 191 Joined: 14-January 03 From: Poole, England Member No.: 144 |
I took a video to help explain better:
https://www.youtube.com/watch?v=uCmqITLZSrM Admin edit: Fixed it for 'ya ... |
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| FlatSix |
May 21 2011, 08:34 AM
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#5
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English Member Group: Members Posts: 191 Joined: 14-January 03 From: Poole, England Member No.: 144 |
Hmm... that didn't work as well as I hoped!
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| FlatSix |
May 21 2011, 08:36 AM
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#6
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English Member Group: Members Posts: 191 Joined: 14-January 03 From: Poole, England Member No.: 144 |
I had the fuel injectors serviced.
The fuel pressure gauge is mounted after the cold injection valve and before the two injectors on the drivers side of the car. |
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| SLITS |
May 21 2011, 08:37 AM
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#7
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"This Utah shit is HARSH!" Group: Benefactors Posts: 13,602 Joined: 22-February 04 From: SoCal Mountains ... Member No.: 1,696 Region Association: None  |
Doesn't sound quite right.
Where is your fuel pressure gauge tapped in? The most common tap, is the tap on the driver's side fuel rail that feeds the cold start valve. EDIT ... negate this, you are playing with a 1.7L. Pull the cold start valve and see if it is leaking. Did you mix up the fuel lines at the tank or in the rear at the firewall? '75 - '76 has the same diameter lines for supply and return (black plastic) as I remember. If you did you are restricting the fuel flow ... supply tap at the tank is a large diameter hole with an extension into the tank with a screen sock over it so it doesn't pick up crap in the tank .... return line is a very small hole but no extension into the tank and no sock. Small hole would not allow for sufficient volume if used as the supply and it can plug easily. From your description, it sounds like you are getting just enough pressure and flow to start the engine and make it run until the fuel pump can no longer supply the volume / pressure required to make it steadily run. Once the injectors start opening, fuel pressure disappears .... something is hooked up wrong. Triggering the fuel pump, with no outlet (engine not running) will build the correct pressure. Just my guesses anyway. |
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| FlatSix |
May 21 2011, 08:38 AM
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#8
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English Member Group: Members Posts: 191 Joined: 14-January 03 From: Poole, England Member No.: 144 |
YouTube video here:
CODE <object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/uCmqITLZSrM?hl=en&fs=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/uCmqITLZSrM?hl=en&fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object> |
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| scotty b |
May 21 2011, 08:47 AM
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#9
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rust free you say ? Group: Members Posts: 16,375 Joined: 7-January 05 From: richmond, Va. Member No.: 3,419 Region Association: None |
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| FlatSix |
May 21 2011, 08:55 AM
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#10
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English Member Group: Members Posts: 191 Joined: 14-January 03 From: Poole, England Member No.: 144 |
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| ConeDodger |
May 21 2011, 09:04 AM
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#11
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Apex killer! Group: Members Posts: 24,396 Joined: 31-December 04 From: Tahoe Area Member No.: 3,380 Region Association: Northern California 
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Pull your relay board and look for greenish crap coming through the tar cover. The problems this causes drove me nuts until McMark had me check it and I found out that I had all that corrosion under there. Tuning was all over the place.
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| FlatSix |
May 21 2011, 09:29 AM
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#12
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English Member Group: Members Posts: 191 Joined: 14-January 03 From: Poole, England Member No.: 144 |
I've just changed the relay board but the symptoms remain the same.
Question - What state should the fuel pump relay be in when the engine is running? I was expecting the plate on the top to be 'down', making contact to run the fuel pump but in this case it is 'up', so is the fuel pump running or not? If this is wrong then maybe the correct signal is not being sent by the FI brain (or at least it is not being received and actioned correctly). |
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| SLITS |
May 21 2011, 09:51 AM
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#13
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"This Utah shit is HARSH!" Group: Benefactors Posts: 13,602 Joined: 22-February 04 From: SoCal Mountains ... Member No.: 1,696 Region Association: None |
In your video, there are a couple of things:
1.) in the middle of the fuel rail there is a 7 mm screw. You could have tapped your fuel pressure gauge at that point instead of cutting the line to the fuel rail. A moot point. 2.) With the engine running, the relay should have been engaged (contact plate down) that you press on. It doesn't appear to be engaged when running ... strange. I have jumped the poles on the relay to make a fuel pump run continuously with the key on and it has never killed the engine. I have been trying to think of why the relay is not engaged, but can't come up with anything at the moment other than a fault in the ECU. In the "start" position of the key, the ECU pulls the relay in for about 1.5 seconds and then releases it. When the engine starts, the ECU sees "proof" and lets the relay be continuously engaged. Again, it should not kill the engine. Hell of a mystery at the moment. All of my wiring diagrams are at the shop so I can't tell you which poles on the relay to jump. Have you tried a different relay as they do go bad? |
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| ConeDodger |
May 21 2011, 10:32 AM
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#14
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Apex killer! Group: Members Posts: 24,396 Joined: 31-December 04 From: Tahoe Area Member No.: 3,380 Region Association: Northern California
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Have you tried switching the relays around...
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| Root_Werks |
May 21 2011, 10:49 AM
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#15
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Village Idiot Group: Members Posts: 8,930 Joined: 25-May 04 From: About 5NM from Canada Member No.: 2,105 Region Association: Pacific Northwest
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You're running off the cold start injector and you have your fuel lines hooked up backwards. It's why you are not getting any psig at the location you've selected and why it will run for a minute or two.
That's my guess! (IMG:style_emoticons/default/biggrin.gif) |
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| FlatSix |
May 21 2011, 10:59 AM
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#16
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English Member Group: Members Posts: 191 Joined: 14-January 03 From: Poole, England Member No.: 144 |
I have swapped the relays around - no difference.
Tomorrow I'll swap the fuel lines over. It's 6pm here now and I've run out of 'my' time. Thanks for all of your help today. |
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| 70-914nut |
May 21 2011, 03:35 PM
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#17
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Member Group: Members Posts: 119 Joined: 15-March 11 From: Elizabeth city nc Member No.: 12,826 Region Association: None |
i had the exact problem. fuel lines we incorrectly connected. i got mine running but ilde is bad.
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| mrgjones |
May 21 2011, 04:02 PM
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#18
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Member Group: Members Posts: 91 Joined: 23-November 09 From: Monterey Member No.: 11,062 Region Association: Northern California |
Somebody correct me if I'm wrong. The fact that the engine remains running with the relay in the "up" position tells me this is the contact position to energize the fuel pump.
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| swl |
May 22 2011, 07:01 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 |
damn this is a weird one!
Lets go back to basics. In order for there to be fuel pressure the pump has to be running. If it is not running the fuel pressure is going to go down in a hurry as pressurized fuel is used up. While the car is running (prior to pushing the relay) the fuel pump has to be running. But if 'down' is contact closed how is this happening? Another weird (to me) thing. How is the fuel pressure staying so high without the pump running? (during the initial part of the video it is at 26psi with nothing running) Should not the pressure drop to zero with the pump off? There is nothing to stop the pressure from bleeding off back through the pump. If you don't touch the relay will the engine continue to run? Did this problem exist before you put the pressure guage in line? Sorry - no answers for you. Going to grab a relay and play with it a bit. |
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| SLITS |
May 22 2011, 07:36 AM
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#20
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"This Utah shit is HARSH!" Group: Benefactors Posts: 13,602 Joined: 22-February 04 From: SoCal Mountains ... Member No.: 1,696 Region Association: None |
QUOTE(swl @ May 22 2011, 06:01 AM)  damn this is a weird one! Another weird (to me) thing. How is the fuel pressure staying so high without the pump running? (during the initial part of the video it is at 26psi with nothing running) Should not the pressure drop to zero with the pump off? There is nothing to stop the pressure from bleeding off back through the pump. There is a check valve in the pump that holds pressure for about 20 mins in the system to make hot starts possible. When the check valve fails, motor will not hot start. If you had a gauge in your system, you would note that on a cold start you begin with "0" pressure. That 1.5 seconds the pump runs on start will build 25 psig very quickly as in a few seconds (if the system is working properly). Relay is nothing but an electromagnetic solenoid. When power is applied, it makes a magnetic field which "captures" the arm and completes the circuit to the fuel pump. |
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