Rodeo won't start

I have a 1996 Isuzu Rodeo with a 3.2L engine. About a week ago my daughter hit a small pile of snow in the road at 35 MPH, and the engine died.

When I checked the Rodeo, I found the fuel pump was not running. I checked the fuel pump fuse, and it was good. I switched out the fuel pump relay 3 times, and it still did not start.

I took voltage readings at the relay socket, and it was reading about 12.6 volts. However, when I crank the engine, there is only .06 volts at the fuse and .06 volts at the fuel pump connector (near the fuel tank).

Apparently there is 12 volts to the relay, but when it reaches the fuse itself there is only .06 volts. Both the fuse and the relay are located in the fuse and relay control box under the hood on the passenger side.

Does anyone have any ideas on what could be the problem or what I should check.

Thanks in advance for your help.

have you been able to get it to start *at all* since the hit? even intermittently?

here's how the fuel pump circuit works which should lead you in the direction of what to check.

when you turn the key to the ON position, the fuel pump *for 2 seconds* gets power from the fuel pump relay via the computer FROM THE BATTERY.

when you crank the engine or when the engine is running (i.e. when the engine is rotating) the fuel pump gets power from the fuel pump relay via the computer FROM THE ALTERNATOR.

so your first check would be to see if it's getting battery voltage when you turn the key to ON. just listen for the sound during that 2 seconds. get someone back there if you can't hear in the seat.

assuming you have this, i would then check all the wires in the charging circuit, including battery terminals and especially the alternator wiring which would be in the line of fire down there. check the connectors at the alternator, you might get lucky and just find one was broken off there.

did you check to make sure the alternator *belt* didn't take a hit?

if the alternator wiring is ok, then consider checking back at the fuel pump, check the connectors and the wiring; but if the 2-second test showed the pump is working, then the wiring would seem to be OK.

worse comes to worse, take the alternator off and get it tested *under load*.

anyway, that's the approach i would take. my bet its the alternator wiring.

//bc

Here is what I checked and in the order I checked it.
1) Checked for fuel pressure at schrader valve with key on and cranking engine -- none
2) Checked fuel pump fuse -- good
3) Checked fuel pump relay -- Switched with 3 different working relays
4) Checked for voltage at fuel pump connecter at fuel tank -- .06 volts with engine cranking and none with key on.
5) Checked for voltage at fuel pump fuse block -- 06 volts with engine cranking and none with key on.

It is not getting voltage or very little voltage with the key on or the engine cranking. The battery is new and charged -- purchased 2 days ago.

I am thinking that it is not getting the signal from the computer. Would that be a correct assumption considering theabove test results?

Thank you for your help and valuable information in tracking down this problem.

How new's your alternator?

...4) Checked for voltage at fuel pump connecter at fuel tank -- .06 volts with engine cranking and none with key on.
5) Checked for voltage at fuel pump fuse block -- 06 volts with engine cranking and none with key on.

It is not getting voltage or very little voltage with the key on or the engine cranking. The battery is new and charged -- purchased 2 days ago....

okay, from my previous post, it's important to narrow this down: do you hear the pump or get voltage at the pump for the first 2 seconds when you turn the key to the ON position ONLY ! ? if you don't what is the voltage back there during those 2 seconds only. and if you do hear the pump working, what pressure reading do you get for those 2 seconds only.

then we can go from there....

//bc

Update -- I had to take the Rodeo to a repair facility, and they were able to get it running.

They found a blown fuse to the computer(15 amp -- labeled ECM). The only problem is that they cannot find out what caused it to blow as it is an intermittent problem. It has blown 2 more times since they replaced the fuse the first time and this usually occurs during hard turns.

They have tried all the usual things like wiggling the harness, but at $79 per hour it can get very expensive very fast. Hopefully it will stay blown, and it will be easy to find the problem.

I want to thank all of you that responded. I appreciate your help in looking for the problem.

Oh,the alternator is the original. My vehicle has about 133K miles on it. Would that cause the computer's fuse to keep blowing?

Before they replaced the ECM fuse there was .06 volts to the fuel pump with the engine cranking.

According to one of the previous posts the computer sends the signal to energize the fuel pump circuit. Once the ECM fuse was replaced the fuel pump circuit was working again.

The problem now is finding what is causing the computer's fuse to blow.

Thank you again for your help in locating the problem.

...cannot find out what caused it to blow as it is an intermittent problem. It has blown 2 more times since they replaced the fuse the first time and this usually occurs during hard turns.

left or right turns? get under there and see what wire is dangling and shorting out on the wheel or steering components on hard turns...

for $80 and hour i'll crawl under there for you...:eek:

//bc

P.S. it could very well not be apparent up on a rack, while it will be on the ground.

Check the O2 sensor wiring.