Fuel pump (Page 1/1)
frosTkilos JUL 02, 08:09 PM
Got an 84 base model.
Car wont start.
I assume it fuel pump.
Take it to mechanic. He says something like the fuel pump works, but the injector is not injecting. Its an electrical problem. Said take it to electrician.
I remember a couple of times when it wouldnt start i would tap the fuse box, then it would start. That doesnt work anymore. I checked the fuses too.
What could the problem be?
Im guessing new relay, new wires, not sure what else.
Whats the easy fix?
Whats the tough fix?
Thank you.
Patrick JUL 02, 08:34 PM

Did you at one time hear the hum of the fuel pump priming for two seconds when you turned the ignition key to Run (not all the way to Start)?

If so, do you still hear that hum now when the key is turned?
theogre JUL 03, 08:42 AM
No Injection can be a "dead" injector, F-pump, ICM, even ECM.

Yea, does make the "Prime noise" when turn the I-key on?

Injector can be dead or has wire problems.

ECM won't run Injection even when pump run to make pressure until ICM works.
ICM can be bad or ECM just think doesn't work because bad wires to it or ECM is bad from crack solder joint etc.

If tap the fuse box & worked, Replace all fuses. Old Fuses can micro crack that you can't see & cause many headaches.
Get fuse kit from real maker like Littelfuse 00940400Z ATO Blade Fuse Super Value Pack
Example: 1 fuse is for ECM & crap fuse won't turn On the ECM.

Pull console out.
Tap the ECM. If helps, remove/install the plugs a few times to work the "pins" may keep it working or not. If not, ECM is "dead" from crack solder joint etc.

Then get a Noid light to see if injector turns On.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

[This message has been edited by theogre (edited 07-03-2024).]

Dennis LaGrua JUL 07, 12:37 PM

quote
Originally posted by theogre:

No Injection can be a "dead" injector, F-pump, ICM, even ECM.

Yea, does make the "Prime noise" when turn the I-key on?

Injector can be dead or has wire problems.

ECM won't run Injection even when pump run to make pressure until ICM works.
ICM can be bad or ECM just think doesn't work because bad wires to it or ECM is bad from crack solder joint etc.

If tap the fuse box & worked, Replace all fuses. Old Fuses can micro crack that you can't see & cause many headaches.
Get fuse kit from real maker like Littelfuse 00940400Z ATO Blade Fuse Super Value Pack
Example: 1 fuse is for ECM & crap fuse won't turn On the ECM.

Pull console out.
Tap the ECM. If helps, remove/install the plugs a few times to work the "pins" may keep it working or not. If not, ECM is "dead" from crack solder joint etc.

Then get a Noid light to see if injector turns On.



Good points but just an added suggestion. You can easily test all fuses without removing them, The two blade fuse used by GM in the 1980's has two contact points on the pull side of the fuse. Using these points just use a volt ohm-meter to check for an open resistance. No resistance-blown fuse.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

theogre JUL 07, 04:47 PM
Yes, those & others has two indents on top to test good or not w/o pulling them.
But...
If you have intermittent problem & tapping the fuse box helps... Then test w/ Ω meter or other methods include using tester/puller come w/ the pack above often won't help you.

Anything touches or disturbs them can make a old ATO(Littelfuse)/ATC(Bussmann) & related fuses to work/pass for awhile.

All fuses are Micro to Milli Ω resistors & over time they crank from stress like many other resistors but circuit doesn't draw enough power to blow them so many times they often look good to you or even pass many test. Normal Ω meters & other tests see as "dead short" because too low Ω & just can't read as a resistor.

If you sure you only need 1 value then cheap to get 1 value.
When you have a car w/ 20+ year old fuses & want/need to replace several to all values, the kit above is often less them buying a few pack individually.

Only buy fuses from real companies like Littelfuse, Bussmann(Eaton) & a few others. No name crap is often Counterfeit & won't blow when they should. YT Bigclive & many others show how bad many of these can be.

You often Don't need to replace Breakers. In this case 1 or 2 metal "fuses" in the fuse box. Those can fail similar to fuses as stated here but a very rare problem. Each breaker cost a lot more the fuses.