Still won't start.

Pyrobuilder · Jul 5, 2015

So I got a 1991 xj a couple days ago knowing that it didn't start. We put money on it being the crank sensor. Put in a new one. Wasn't the problem. It has a new fuel pump. It runs. I replaced the asd relay. Nothing happened. Still at the no fuel no spark stage. I know the pump works because I took the relay out and used a wire for the connection. Pressure built. I moved the wire to another terminal where the relay would go and I heard something else run then stop. Still not sure what it was. What could the issue be?

ehall · Jul 5, 2015

You need to check if the injectors are firing. You can get a mechanic's stethoscope at NAPA or Harbor Freight for less than $20, otherwise use a piece of metal rod or a long screwdriver and touch it to the injectors and listen for click-click-click noise. If the injectors are not firing then its one of (a) cam sensor in the dist, (b) crank sensor, (c) ASD relay, or (d) ECM. If the injectors are firing then its ignition problem, like coil or something

Pyrobuilder · Jul 6, 2015

ehall said:
You need to check if the injectors are firing. You can get a mechanic's stethoscope at NAPA or Harbor Freight for less than $20, otherwise use a piece of metal rod or a long screwdriver and touch it to the injectors and listen for click-click-click noise. If the injectors are not firing then its one of (a) cam sensor in the dist, (b) crank sensor, (c) ASD relay, or (d) ECM. If the injectors are firing then its ignition problem, like coil or something

Alright, since I posted earlier I put a junkyard ecm in. It really tried to start. Replaced the spark plugs which were loose and out of spec, rotor, cap and wires. switched the coil with another one that we got at the junk yard since we were there. it will run if ether is being sprayed slowly. the fuel pressure is staying the same so I am leaning towards Injectors now.

Thanks, Daniel

ehall · Jul 6, 2015

Check fuel pressure, you can get a loaner pressure tester from Autozone or buy one from HF for less than $30

Also clean your IAC

Pyrobuilder · Jul 6, 2015

Got the pressure tester. its hovering when "running" on ether at 32ish. what is the IAC?

Pyrobuilder · Jul 6, 2015

ehall said:
Check fuel pressure, you can get a loaner pressure tester from Autozone or buy one from HF for less than $30

Also clean your IAC

ehall · Jul 6, 2015

Pyrobuilder said:
Got the pressure tester. its hovering when "running" on ether at 32ish

That's normal pressure at idle for that era

. what is the IAC?

Idle Air Controller, its the thing on the side of the throttle body, its how the computer controls air flow when your foot is not working the gas pedal (air pedal, on fuel injection cars). It has a pintle on a motor, the computer bumps the motor to make the pintle open and close as needed. You can see the inlet side above the butterfly valve, the outlet is on the other side of the butterfly. Car needs fuel spark and air, if the IAC is gummed up the computer can't meter the airflow and the engine won't run

Pyrobuilder · Jul 6, 2015

ehall said:
That's normal pressure at idle for that era

Idle Air Controller, its the thing on the side of the throttle body, its how the computer controls air flow when your foot is not working the gas pedal (air pedal, on fuel injection cars). It has a pintle on a motor, the computer bumps the motor to make the pintle open and close as needed. You can see the inlet side above the butterfly valve, the outlet is on the other side of the butterfly. Car needs fuel spark and air, if the IAC is gummed up the computer can't meter the airflow and the engine won't run

Alright that is easy to understand. So would it cause the problems I'm having or at least to contribute to them? Can I just clean it with carb cleaner or something like that and small brush?

ehall · Jul 6, 2015

Whats the current situation? You have spark enough to ignite starter fluid so its not an ignition or timing problem. What color is the spark? Whitish blue is better than orange on these cars. You have what seems to be correct fuel pressure. Might check to make sure injectors are firing, or that they aren't leaking and flooding the cylinders. After that, lack of air flow would definitely prevent it from starting. You could try standing on the gas pedal (air pedal) and see if it starts when operated manually.

8Mud · Jul 6, 2015

How old is the fuel? It can turn to something resembling jelly and clumps if it is old enough.

ehall · Jul 6, 2015

Thats good advice, I just brought a Chevy Caprice back to life that had sat for 4 years, fuel had gone watery, had to run it out with the pump, also had to clean the injectors because they were gummed up.

Pyrobuilder · Jul 6, 2015

8Mud said:
How old is the fuel? It can turn to something resembling jelly and clumps if it is old enough.

its been sitting since december. not too long but there was not fuel in it really we have put maybe 5 gal in of non ethanol that we had in cans.

Pyrobuilder · Jul 6, 2015

ehall said:
Thats good advice, I just brought a Chevy Caprice back to life that had sat for 4 years, fuel had gone watery, had to run it out with the pump, also had to clean the injectors because they were gummed up.

would that be something that I could clean with brake cleaner or something along those lines?

ehall · Jul 6, 2015

If you want to fully eliminate fuel problems, unbolt the rail and wiggle the injectors out of their holes, then lay the whole thing on a piece of cardboard and crank the engine, then look for uneven spray pattern, dripping after the fact, etc. It seems unlikely to be injector related, you should get some starts, running rough, etc. If you get nothing then there is a clog in the line or something, but your earlier pressure test should have eliminated that.

Pyrobuilder · Jul 7, 2015

alright, so how often is it that a fuel pump is put in wrong? how many volts should be going to the pump and is it easy to mix up fuel lines? the pump was replaced before I got it, that's why im asking.

Pyrobuilder · Jul 7, 2015

ehall said:
If you want to fully eliminate fuel problems, unbolt the rail and wiggle the injectors out of their holes, then lay the whole thing on a piece of cardboard and crank the engine, then look for uneven spray pattern, dripping after the fact, etc. It seems unlikely to be injector related, you should get some starts, running rough, etc. If you get nothing then there is a clog in the line or something, but your earlier pressure test should have eliminated that.

ehall · Jul 7, 2015

Its possible on a 91 to put the supply and return lines on backwards, both of them are right there

Pyrobuilder · Jul 7, 2015

ehall said:
Its possible on a 91 to put the supply and return lines on backwards, both of them are right there

if the lines are on backwards, would the system still pressurize and somewhat run?

ehall · Jul 7, 2015

I wouldn't think so but it might

You can verify by disconnecting the lines at the rail and turning on the pump. The supply line from the pump connects directly to the rail, the return line connects to the regulator

Pyrobuilder · Jul 7, 2015

ehall said:
I wouldn't think so but it might

You can verify by disconnecting the lines at the rail and turning on the pump. The supply line from the pump connects directly to the rail, the return line connects to the regulator

Alright man I'll be sure to try that when I get home later today

Still won't start.

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