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bransky04
New User
Nov 26, 2010, 3:50 PM
Post #1 of 4
(1291 views)
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intermittent start
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2004 ford ranger pickup 4.0l sohc 6cyl. xlt ext. cab. 30,000 miles several months ago stopped in store came out about 20 minutes engine started as always ran a few seconds then died and would not restart, cranked fine but would not turn over. waited about an hour engine started as if it were out of fuel, sputtered then ran smoothly. vehicle ran perfectly for about a month then same problem. stop at store come out and same nonstart , then start about an hour later. this has happened 4 times and this last time after waiting over 5 hours had to have vehicle towed home. checked fuel pump relay, inertia switch, fuses, and power at fuel pump all ok .what could be causing this on again off again issue?
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Hammer Time
Ultimate Carjunky
/ Moderator
Nov 26, 2010, 4:04 PM
Post #2 of 4
(1283 views)
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Re: intermittent start
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You have to go back to basics
All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.
Every engine requires spark, fuel and compression to run. That's what we have to look for.
These are the basics that need to be tested and will give us the info required to isolate a cause.
1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.
2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.
3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.
Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Elise Car Tech
User
Nov 26, 2010, 9:21 PM
Post #3 of 4
(1259 views)
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Re: intermittent start
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This a “Hot Soak” starting problem. A fuel leak down condition is taking place. The leak down is secondary to one or more leaking fuel injectors, a failing fuel pressure regulator, or a failing fuel pump check valve. Loss of fuel pressure causes an air bubble to form in the fuel circuit that has to be flushed out before the truck can start. The truck won’t start for as long as the bubble remains. Let’s start with fuel pressure psi readings. Using a fuel pressure gauge confirm the static, residual, and running fuel pressure psi readings below. After that you’ll have to post the results of a “Fuel Pressure Leak Down” test. Let us know if you don’t know how to do this test, and one of us will walk you through it.
(Static) KOEO 40-65 PSI
Running 40-65 PSI
(Residual) Pressure must be within 5 PSI of above values for one minute after fuel pump is off.
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(This post was edited by Sidom on Nov 26, 2010, 10:08 PM)
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Sidom
Veteran
/ Moderator
Nov 26, 2010, 10:08 PM
Post #4 of 4
(1255 views)
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Re: intermittent start
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This will be my final warning....
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