74 2.0L, Running Very Rich, owner quite confused, need diagnostic help |
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74 2.0L, Running Very Rich, owner quite confused, need diagnostic help |
drumsticks2112 |
Sep 20 2009, 12:56 PM
Post
#21
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Newbie Group: Members Posts: 7 Joined: 29-October 08 From: New London Member No.: 9,704 Region Association: Upper MidWest |
Car fires without a problem, but idles quite rough, and runs very rich, so much so that when the it settles down to normal idles, it floods out. MPS was replaced with a used but tested one recently. When it was last running ( a year ago) it ran a little rich, but nothing like this.
As of now, the CHT is not connected. When it is connected, the RPMs jump up to 4000 and stay there. When the CHT is bypassed with direct grounding of the harness, the results are the same as with the sensor being disconnected. I have no reason to suspect the injectors, FPR, Decel Valve, or the MPS. Any and all advice is welcome. -Todd |
r_towle |
Oct 2 2009, 01:13 PM
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#22
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Custom Member Group: Members Posts: 24,624 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
There is no fuel pressure sensor...a fuel pressure regulator, yes.
The TPS is the throttle position switch. The static fuel is from the cold start valve that may be stuck open...I ended up there also...after fixing everything else. that is kicked off by the ambient air temp sensor (mounted under the plenum) Try routing around the cold start injector...unplug it electrically, remove the fuel from it (add a long line to route around it... I did that...it stopped running super rich. Rich |
CHAZT54 |
Oct 2 2009, 03:42 PM
Post
#23
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CHAZT54 Group: Members Posts: 19 Joined: 29-December 08 From: New London, Wisconsin Member No.: 9,878 Region Association: Upper MidWest |
There is no fuel pressure sensor...a fuel pressure regulator, yes. The TPS is the throttle position switch. The static fuel is from the cold start valve that may be stuck open...I ended up there also...after fixing everything else. that is kicked off by the ambient air temp sensor (mounted under the plenum) Try routing around the cold start injector...unplug it electrically, remove the fuel from it (add a long line to route around it... I did that...it stopped running super rich. Rich yes - the fuel pressure sensor was a mis-statement. I will check out the cold start valve as you suggested. Could the pressure reg. be set too high? I haven't touched it since I bought the car a year ago so I didn't suspect a problem there. THANKS RICH. |
CHAZT54 |
Oct 5 2009, 12:21 PM
Post
#24
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CHAZT54 Group: Members Posts: 19 Joined: 29-December 08 From: New London, Wisconsin Member No.: 9,878 Region Association: Upper MidWest |
There is no fuel pressure sensor...a fuel pressure regulator, yes. The TPS is the throttle position switch. The static fuel is from the cold start valve that may be stuck open...I ended up there also...after fixing everything else. that is kicked off by the ambient air temp sensor (mounted under the plenum) Try routing around the cold start injector...unplug it electrically, remove the fuel from it (add a long line to route around it... I did that...it stopped running super rich. Rich yes - the fuel pressure sensor was a mis-statement. I will check out the cold start valve as you suggested. Could the pressure reg. be set too high? I haven't touched it since I bought the car a year ago so I didn't suspect a problem there. This 914 is strictly a summer weekender and does get run once freezing temps set in. In stead of re-routing a fuel hose over to the opposite fuel rail, couldn't I just remove that hose and cap off both fuel rails at the tee? I would then leave the larger hose hooked up to the cold start valve- fuel stem & elect. connect would be capped off. Would that work OK? THANKS RICH. |
r_towle |
Oct 5 2009, 04:48 PM
Post
#25
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Custom Member Group: Members Posts: 24,624 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
There is no fuel pressure sensor...a fuel pressure regulator, yes. The TPS is the throttle position switch. The static fuel is from the cold start valve that may be stuck open...I ended up there also...after fixing everything else. that is kicked off by the ambient air temp sensor (mounted under the plenum) Try routing around the cold start injector...unplug it electrically, remove the fuel from it (add a long line to route around it... I did that...it stopped running super rich. Rich yes - the fuel pressure sensor was a mis-statement. I will check out the cold start valve as you suggested. Could the pressure reg. be set too high? I haven't touched it since I bought the car a year ago so I didn't suspect a problem there. This 914 is strictly a summer weekender and does get run once freezing temps set in. In stead of re-routing a fuel hose over to the opposite fuel rail, couldn't I just remove that hose and cap off both fuel rails at the tee? I would then leave the larger hose hooked up to the cold start valve- fuel stem & elect. connect would be capped off. Would that work OK? THANKS RICH. In a word, NO. Follow the hoses back to the fuel pump and read the manual to get a detailed explaination of why that will not work. It will kill off your pump for one thing with no fluid in that part of the pump. Rich |
CHAZT54 |
Oct 6 2009, 07:47 AM
Post
#26
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CHAZT54 Group: Members Posts: 19 Joined: 29-December 08 From: New London, Wisconsin Member No.: 9,878 Region Association: Upper MidWest |
There is no fuel pressure sensor...a fuel pressure regulator, yes. The TPS is the throttle position switch. The static fuel is from the cold start valve that may be stuck open...I ended up there also...after fixing everything else. that is kicked off by the ambient air temp sensor (mounted under the plenum) Try routing around the cold start injector...unplug it electrically, remove the fuel from it (add a long line to route around it... I did that...it stopped running super rich. Rich yes - the fuel pressure sensor was a mis-statement. I will check out the cold start valve as you suggested. Could the pressure reg. be set too high? I haven't touched it since I bought the car a year ago so I didn't suspect a problem there. This 914 is strictly a summer weekender and does get run once freezing temps set in. In stead of re-routing a fuel hose over to the opposite fuel rail, couldn't I just remove that hose and cap off both fuel rails at the tee? I would then leave the larger hose hooked up to the cold start valve- fuel stem & elect. connect would be capped off. Would that work OK? THANKS RICH. In a word, NO. Follow the hoses back to the fuel pump and read the manual to get a detailed explaination of why that will not work. It will kill off your pump for one thing with no fluid in that part of the pump. Rich OK - so I need to replace the hose feeding the CSV with a longer one that will reach accross the engine and connect to the tee on the opposite fuel rail? - and cap off the fuel line barb on the CSV and leave the elect. wires disconnected? |
r_towle |
Oct 6 2009, 01:18 PM
Post
#27
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Custom Member Group: Members Posts: 24,624 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
There is no fuel pressure sensor...a fuel pressure regulator, yes. The TPS is the throttle position switch. The static fuel is from the cold start valve that may be stuck open...I ended up there also...after fixing everything else. that is kicked off by the ambient air temp sensor (mounted under the plenum) Try routing around the cold start injector...unplug it electrically, remove the fuel from it (add a long line to route around it... I did that...it stopped running super rich. Rich yes - the fuel pressure sensor was a mis-statement. I will check out the cold start valve as you suggested. Could the pressure reg. be set too high? I haven't touched it since I bought the car a year ago so I didn't suspect a problem there. This 914 is strictly a summer weekender and does get run once freezing temps set in. In stead of re-routing a fuel hose over to the opposite fuel rail, couldn't I just remove that hose and cap off both fuel rails at the tee? I would then leave the larger hose hooked up to the cold start valve- fuel stem & elect. connect would be capped off. Would that work OK? THANKS RICH. In a word, NO. Follow the hoses back to the fuel pump and read the manual to get a detailed explaination of why that will not work. It will kill off your pump for one thing with no fluid in that part of the pump. Rich OK - so I need to replace the hose feeding the CSV with a longer one that will reach accross the engine and connect to the tee on the opposite fuel rail? - and cap off the fuel line barb on the CSV and leave the elect. wires disconnected? That is exactly what I did. Its about 2-3 feet of new hose and a few clamps...done. Use the old hose and old clamps to close off the cold start injector just in case its stuck open. I unplugged the elec first and that made no difference for me, so it may have been stuck open or leaking on mine...I never bothered to check. Again, it really only comes into play when its really cold...otherwise its never used. I suspect that is why it gets rusted and stuck...its used very rarely. Rich |
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