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Old November 18th, 2017, 13:38
Intellect Intellect is offline
NAXJA Forum User
Join Date: Oct 2016
Location: Tampa Florida
Posts: 185
Re: New fuel pump, new regulator, still has fuel pressure issue..

Originally Posted by Ecomike View Post
You need to get a helper, one turn the key, one under the hood checking spots for voltage when the key is turned to run (1/2 turn as you have called it). There is no electrical-fuel check valve.

Your ignition switch (not the key lock part, but the electrical start-run acc slide switch buried deep under the dash on top of column may be going bad, and the wires/contacts attached to from over heating over 2 decades....

Or it may be a dirty weak electrical connection anywhere between the battery, the computer and certain relays. But it sounds like the computer is getting a rand late pre start signal voltage that makes me suspect the ignition switch first. The fact that turning it to run and it taking 1-120 seconds to power up the timed 3 second power to prime the pump must be a low wandering voltage signal to the computer that powers and times the fuel pump relay. It would not fuel pump or fuel pump relay wiring as the late power up means the computer is sending fuel on signal late!!!! So it has to be the ECU or power to the ECU like the ignition switch. Also check for any loose corroded fuses!!! Check the ignition switch first or just replace it, they are cheap. Also make sure there is power to the ECU at the fuse when you turn the ign-switch!!! To both sides of the fuse, when the fuel pump does not run right away!!! You need to low or missing voltage in the path to the computer at times when the fuel pump fails to cycle on right away. When you do you will know what path has a bad connection to the ECU, or the Ign-switch, or you will know of the Ign-switch or ECU is bad.

If it was me I would buy an Ign-switch and swap it, after testing the fuses and contacts in the fuse boxes that power the ECU. The ECU is what times and powers the prime!!!! Since the timing is variable, it is a power at the ECU issue (wiring, corroded contacts, intermittent contacts) or the Ign switch IMHO.

Nothing after the ECU could change or delay the fuel pump prime on start cycle, and it never restarts a prime cycle till you turn the ign switch off!!!

Any remaining bleed off, if it is even an issue, is not related to your prime power to the pump problem!!!

It is possible the prime timer chip, wiring, electronics in the ECU is going bad, But I'd bet on it being dying, burned, corroded contacts in the ignition switch that powers the ECU, before any thing else.
WOW that was informative, i did a quick read, but ill sit down and digest it later. But the gist is i more than likely have two issues at hand. Which is good..ish? To here LOL.

The pump taking a minute to turn on happens VERY VERY rarely. So ill adress the bleed off issue for now. Im putting an inline check valve in and reporting back.

I ran another test, with a fancy gauge set I bought. Right after the fuel filter. And BAM bleed off. Im guessing faulty pump, which im tired of replacing, so check valve it is!

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