Is this the dreaded 914 vapor lock?, Asking for your ideas and thoughts |
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Is this the dreaded 914 vapor lock?, Asking for your ideas and thoughts |
Artfrombama |
Jul 14 2024, 05:04 PM
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#1
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Member Group: Members Posts: 156 Joined: 21-January 24 From: Alabama Member No.: 27,870 Region Association: South East States |
Drove my 914 to a PCA function yesterday morning, 93f and humid.
After driving on the interstate at 70-75mph for around 45 miles I exited and the motor died. I had enough momentum and coasted into a gas station/convenience store where I topped off the tank and tried to restart the car, no luck. The car would fire, run a few seconds and die then refused to re-start for another 10-15 minutes then the same scenario again. No tools to diagnose or repair. While waiting on AAA for three hours (another story) I would occasionally try to start the car with the same results. Today, car started normally, runs normally. 1974 L-jet, original three bung fuel pump, original location. 500 miles on new tank, sock, filter, ss lines. |
wonkipop |
Jul 15 2024, 07:15 PM
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#2
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Advanced Member Group: Members Posts: 4,611 Joined: 6-May 20 From: north antarctica Member No.: 24,231 Region Association: NineFourteenerVille |
so let me get this right with the test you did.
you unplugged fuel regulator and plugged line and tested and got 43 psi. that means your pump could only muster 43 psi before it was blowing out the back door. a good one will get to about 60-70 psi. thats basically the same test i did on my rebuilt pumps if i understand you right. we were using a guage that had an adjustable tap on it. setting it to values of first 28 then 35 simulating the fpr. it was making it. then we kept cranking it until we got it to shoot out port 3. happened at 60-70 depending on the pump i was testing. additional to the ultimate pressure test the whole deal has to be able to do those two values i posted. theoretically with the fuel pressure regulator plugged in and being tested it should still be able to make the pressures of 28 and 35 in the injector line even with weaker value of 43 max made by pump. its a bit of a close margin but its there. thats if the fpr is good. unless that 43 is not something its able to make consistently. i'm reading your second test again carefully. so you are saying that once again you plugged line before fpr. ie ultimate test of pump against completely closed line. and all it could muster was 14psi. so was blowing out the back door at 14 psi. if so. pump ratshit. probably in that spring thing. either backflowing down supply line frpm tank because rubber tip on pin is rooted or not there or not seated properly. or the spring is catching and the whole jigger is jammed open letting it flow out of the final escape port back to the tank. |
Artfrombama |
Jul 15 2024, 09:52 PM
Post
#3
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Member Group: Members Posts: 156 Joined: 21-January 24 From: Alabama Member No.: 27,870 Region Association: South East States |
so let me get this right with the test you did. you unplugged fuel regulator and plugged line and tested and got 43 psi. that means your pump could only muster 43 psi before it was blowing out the back door. a good one will get to about 60-70 psi. thats basically the same test i did on my rebuilt pumps if i understand you right. we were using a guage that had an adjustable tap on it. setting it to values of first 28 then 35 simulating the fpr. it was making it. then we kept cranking it until we got it to shoot out port 3. happened at 60-70 depending on the pump i was testing. additional to the ultimate pressure test the whole deal has to be able to do those two values i posted. theoretically with the fuel pressure regulator plugged in and being tested it should still be able to make the pressures of 28 and 35 in the injector line even with weaker value of 43 max made by pump. its a bit of a close margin but its there. thats if the fpr is good. unless that 43 is not something its able to make consistently. i'm reading your second test again carefully. so you are saying that once again you plugged line before fpr. ie ultimate test of pump against completely closed line. and all it could muster was 14psi. so was blowing out the back door at 14 psi. if so. pump ratshit. probably in that spring thing. either backflowing down supply line frpm tank because rubber tip on pin is rooted or not there or not seated properly. or the spring is catching and the whole jigger is jammed open letting it flow out of the final escape port back to the tank. Yeh Sunday I got in the car, hit the key and immediately fired and idled great. I didn’t drive the car because it had been raining. Got under the car and checked the fuel hoses from the tank, we’re ok. Hooked up my pressure gauge to the test nipple and read 23psi, clamped the hose before the PR with hemostats and read dead head pressure, 43psi. Then I checked pressure straight out of the pump 14psi |
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