How to check relays

Hey, I'm having an issue with my Rodeo not starting. At first suspected fuel pump, as it seemed not to be getting fuel. Had fuel filter replaced, had fuel pump checked and it's fine. Last input I had was to check relay(s) and then if they are OK, clean out throttle body.

Anyone know how to direct me to check the relays?

Any particular year or engine?

Mike

Any particular year or engine?

Mike

V6 3.1 L 1992 Rodeo S 4x4

My 92 Rodeo had this same problem. Sometimes it would start, other times it would just crank away until I drained the battery.

What I found was this:

On start the computer sends 'prime pulse' signals to the injectors, just enough fuel to get the engine running, then it begins normal run mode, where fuel is delivered according to the readings of all engine sensors.

After days of troubleshooting, replacing relays, fuel filter, testing fuel pump etc, I found that when I cranked the engine, there were only two short prime pulses to the injectors, with two tiny squirts of fuel, then it would stop.

Alas, continuing to hold in crank position would not send any more fuel to the TBI, never starting the vehicle.

I have not found a fix for this yet, but two things work for me:

- ether. Spray some ether down the TBI and it starts no problem
- quick start. Turn the key 2 or 3 times in quick succession, which does 2 prime pulses for each quick turn of the key and stores just enough fuel in the upper chamber of the TBI. Then start normally. This works religiously for me as well.

Note that when my vehicle turns to 'run' mode, it runs perfectly great. It's only at that startup sometimes (usually the colder it is) that I have my issues. Get it running, and it runs like a kitten at 750 RPM :o)

HTH,

Steve

best way to check relay is to swap it with another one like it that you know is working

Found relay and it was not working properly- Replaced relay. Still same problem, turns over but won't get gas to start. If we put fuel directly into carb, starts but won't keep running. Am buying throttle body kit to clean and replace rings etc.

Any other ideas to check? NEED to get this thing running so I can taxi around my 2 girls! eeeks :banghead:

Did you check fuel pressure before and after the filter? I know you say the filter is new, and the pump is good, but I'd still check the pressure in run (with engine off) and in crank.

If that's good, put a voltmeter across the injector electrical wires. I get about 1.5 volt pulses in start position, and about 1.5 volts steady in run (only with vehicle running though).

If you are getting electricity to the injectors, then keep looking for fuel delivery problems, but at least it's one more thing that's been checked.

While doing the fuel pressure checks, try to test the pressure as close as possible to the TBI unit. If there is pressure there, then you may need to have the fuel regulator looked at.

Steve

Disconnect The Connector At The Fuel Pump Clean The Terminals Slightly Twist The Male Side Reconnect Should Start