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Discussion Starter · #1 ·
Hi guys, just joined the forum. I have a really beat up 1991 rodeo 3.2 v6 auto transmission that I love no matter how many problems it has right now. My mom had it and she gave it to me with alot of problems (its been sitting still for about 2 years). we live in costa rica so the roads beat most cars to dust, but these isuzus are so dam tough it doesn't seem to worry it to much.

anyway, i have a major problem right now that i need to know a few things about and any help would be GREATLY appreciated.I had it fixed by a mechanic about 9 months ago and it was working steady and it has stoped starting again. when you flick into ignition you cannot hear the fuel pump going, and if you pour gas into the carby it will crank up for 5 seconds, so it has to be the fuel delivery.

a friend checked the relay for me and said it was fine. soon we are going to drop the tank and give the pump a gander. I was just wondering what the possibilities are for the pump not activating. corroded wiring maybe?
 

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A 91 Rodeo has two fuel pump relays, relay # 1 is energized by the Electronic Control Module (ECM) and relay #2 by an oil pressure switch. Relay #1 is used to initially start the pump and get the engine running and #2 keeps it running as long as there is oil pressure. Since it runs long enough to develop oil pressure when you prime the engine, the most probable cause of your problem is a defective fuel pump.
Verify this by removing one of the relays and applying +12 VDC directly to pump through the relay socket pin that supplies the pump. The relay wiring schematic may be on the relay case, otherwise you will have to figure out which is the correct pin. Fuel pump power for each relay comes from a separate fuse, so a blown fuse is not the problem.
 

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Discussion Starter · #3 ·
the fuel pump never engages, in order to test to see if its an engine problem we manually pour gasoline into the carbeurator, i duno if these rodeos alsoo come in direct injection, but this 1 has a carbeurator.

So with the small amount of gas that we put into the carb, the engine cranks no problem. Once it burns up it dies

the fuel pump cannot be heard at all at any time

thank you for your input, i did not know that there are 2 relays. Will have a look tomorow

edit: the fuel pump never seemed that irratic or anything, 1 day it just decided that it wasnt gona work, is this normal for fuel pumps?
 

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It is possible to have a bad connection from the pump to the relay, but difficult to find, and you end up dropping the tank to get to the connector anyway. Once you get tank dropped, check for 12 V in harness to the pump by probing with VOMeter when key is first turned on...you may need an assistant for that part. If you are getting that 12 V for a couple of seconds then likely it is the pump that is bad. Pumps are funny, some just quit, others are intermittent but easiest to diagnose is when they just quit!
HTH One guys opinion.
 

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Alternator!!!!!!!! Do a search this has been written about often. The alternator can charge fine but not send voltage to trip the fuel pump relay on the special wire.
 

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Discussion Starter · #6 ·
hmmm alternator, i never mentioned that i also have the blinking check transmission light of death once every second start. I was reading that faulty electronics can set it off, including an alternator, maybe these 2 problems ARE related after all.

but damit i hope not.

one thing i will say though is that faulty wiring would definatley not surpise me because we live on a costa rica beach, FAMOUS for its corrosive salty air. things start to rust in 1 month if you dont wash it. its terrible. Every1 hates new cars with electronics here the wiring goes out very often.

just wish i could swap out my power windows for good ol wind ups.
 

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Discussion Starter · #7 ·
ok i got the service manual and i found at the placement of the relay, here's a pick of my fuse box in the engine compartment



the brown 1 is the "ECM" according to the manual, which im geussing is the 1 mentioned by buster 28, it is a 6 pin as shown. the 1 below it is the so called fuel pump relay which is 5 pin, which i am geussing is the oil pressure regulated switch.

you might also notice that the brown 1 has a little hole in it. would that be enough to signify a dead relay? i am dubious

so now i have 2 questions, does any1 know on which of these relays is the power link and which is the control unit, and 2 in which socket pins would i do the direct pump test?

EDIT wrong... the ecm relay isnt the first relay box. service manual has 2 fuel pump 1s and the ecm as its own, it sais something about it being in the dash will check that
 

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Discussion Starter · #8 ·
UPDATE:

i checked the relays the other day and they are fine, the next day we jacked up the back took off both the wheels and droped the tank, we direct connected the tank to the battery and it worked, with a little whirrr noise.

So, pump is fine, relays are fine, must be the alternator or the wires. I do howwever doubt it is the alternator because the pump does not engage on ignicion.

New update:alternater is fried, this must be the culprit
 
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