1.8 l-jet fires, but dies within seconds, tried searching :-/ |
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1.8 l-jet fires, but dies within seconds, tried searching :-/ |
thatguywiththedatsun |
Mar 21 2014, 01:36 PM
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#1
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Newbie Group: Members Posts: 21 Joined: 21-March 14 From: Memphis, TN Member No.: 17,144 Region Association: None |
I've been looking for a 914 for a few months now, but life has been in the way. I found one last month that seems to be a good starting point, but I'm having trouble getting it to stay running atm. Seems like it's probably the l-jet system being out of adjustment or leaky, faulty sensors, or some old corroded electrical connectors. The question is; where?
I'm getting a buzzing sound with the key turned to "on" which I initially thought was the seatbelt interlock buzzer everyone seems to be so fond of, but upon closer inspection... it's coming from the injectors..? If i unplug the noisy injector, another one starts buzzing. There's no noise from the fuel pump at this time with the key on. The fuel pump relay, and power supply relay on the board were nowhere to be found when I got the car. I went ahead and bought a few new ones to get it back to stock wiring, but I'm really having trouble deciphering the current flow diagrams. (You guys seems to have a reference system to the pins in every connector, or which specific relay you're referencing. Is there a diagram for this somewhere, or are the labels just buried under the grime in this car?) If i hot wire the double relay (86d, 88d?) to the + battery post, the fuel pump will run, but this doesn't change my "start, rumble rumble, die" situation at all. I have a feeling that there is an area in the wiring that has been altered which, if put back to stock, would rectify the problems I'm having... It's just a matter of finding it and fixing it. Any suggestions? What I have done: -compression test: 125,130,90,135 - hoping it will improve pending a valve adjustment? -tested the coil and wires for spark - checks out fine... nice and strong -tested fuel pressure - 43psi holding steady for several minutes after the test (p.o. said he'd recently had the fuel pump replaced, but didn't mention why (IMG:style_emoticons/default/dry.gif) ) -renewed all the l-jet vacuum hoses and put hose clamps on every connection -taken care of a few obvious electrical bugs (missing/rusty relays, broken wires, etc) -checked the head temp sensor spade connection, but where does the other end of that connection terminate on the relay board? -checked afm resistance. - With key on, if I move the flap by hand, the fuel pump does run, but there is no 1.5 seconds of priming with the key on, just the annoying injector buzz. Thanks in advance for the help! I'll be much better off if someone could just explain the 'pin 13/relay 74/etc. references to me. (IMG:http://www.914world.com/bbs2/uploads_offsite/lh5.googleusercontent.com-17144-1395430598.1.JPG) (IMG:http://www.914world.com/bbs2/uploads_offsite/lh5.googleusercontent.com-17144-1395430599.2.JPG) (IMG:http://www.914world.com/bbs2/uploads_offsite/lh3.googleusercontent.com-17144-1395430600.3.JPG) (IMG:http://www.914world.com/bbs2/uploads_offsite/lh3.googleusercontent.com-17144-1395430600.4.JPG) |
Dave_Darling |
Mar 21 2014, 04:17 PM
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#2
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914 Idiot Group: Members Posts: 14,986 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California |
Here's a link to a diagram of the FI wiring harness, offered by Jeff Bowlsby: https://bowlsby.net/914/WiringHarnesses/Har...FI_EC74-1.8.pdf
BTW, if you suspect your FI harness, go to https://bowlsby.net/914/WiringHarnesses/ and click the links to contact Jeff. It looks like he may now offer his "rebuild" service (the D-jet harness is 90%+ brand-new parts after he's done, so I'm not sure rebuild is the right word) for the L-jet stuff. The L-jet fuel pump runs under 2 circumstances: 1- the key is turned to "start"; 2- the flap in the air-flow meter is open (and the key is "on"). You can check the pump by turning the key on and pushing the flap in the AFM open by hand. There is a box with four resistors in it that also hangs off the battery tray; those are used to drop the power to the injectors. Make sure the one side of those has +12V when the key is on. The injectors are really easy to remove from the manifold; one nut holds each one on. Remove both injectors from one side of the motor and stick them in jars. Crank the starter; look for squirts of fuel coming out of the injectors or at least look for fuel in the jars after cranking. Note that there is a white wire in the FI harness that goes to the (-) terminal on the coil. That carries the signal from the points to the FI, telling it when to open the injectors. You won't get fuel without that hooked up, except possibly through the cold-start injector which dumps directly into the intake manifold. --DD |
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