Starting issues 81 720

[81SVN20]

I'm having issues with my truck here is the rundown, it started up yesterday and ran for about 30 seconds then died out so I restarted it and ran again for about 20 seconds then died, now my truck will not start up it only cranks over.... I check the positives on both coils and both have power but one coil doesn't have a spark and the other has a spark but weak when I crank the engine. Could this be my coils? I appreciate the help....

 

Thanks in advance guys!

[Twinpilot001]

fuel @ carb?? check fuel pump output??

[datzenmike]

Truck should still start even with only one coil, but run poorly.

 

Look at the front of the carb, is the gas up to the dot on the sight glass? Does it have gas???

 

No gas.................. is there gas in the tank? Is the fuel pump working with the key on???

 

Gas in tank but fuel pump not working... is probably the fuel pump relay located above pass side kick panel under right side of dash

 

Gas in tank and fuel pump working..... change fuel filters. There's on between pump and tank and one in the bottom of the electric pump.

[81SVN20]

Truck should still start even with only one coil, but run poorly.

 

Look at the front of the carb, is the gas up to the dot on the sight glass? Does it have gas???

 

No gas.................. is there gas in the tank? Is the fuel pump working with the key on???

 

Gas in tank but fuel pump not working... is probably the fuel pump relay located above pass side kick panel under right side of dash

 

Gas in tank and fuel pump working..... change fuel filters. There's on between pump and tank and one in the bottom of the electric pump.

 

Thanks Mike I will check the level of the gas through the glass and I have more than 1/2 tank of fresh gas and a brand new filter... I dont have any relay on the right side as I checked before I posted and I dont seem to find an electic fuel pump near the tank again my engine is the Z22 I see the line coming from the tank and then connected to mechanical fuel pump near the intake and then another return line to the tank.... I will remove the return line and then crank and see if gas will shoot out as well just to also check if the fuel pump is working...

[datzenmike]

Yes, I forget the Z22 also has a mechanical pump. All the 720s up here were electric pumps.

 

If carb has fuel I'll assume it's an electrical problem.

[81SVN20]

Yes, I forget the Z22 also has a mechanical pump. All the 720s up here were electric pumps.

 

If carb has fuel I'll assume it's an electrical problem.

Im going to be replacing the main negative ground wire from the battery to the body then to the engine and then replacing the coils and rotor and distributor cap that way I rule out not having good ground to have good 12 volts of power for the coils....  then Im still going to check on the fuel to see if there is any inside the glass and making sure the mechanical fuel pump is pumping fuel too....

 

Then Im sure it should fire right up! :thumbup:

[wayno]

I would check the fuel first, don't just throw money at it, figure out what it is not, one thing at a time.

[datzenmike]

I agree, get expensive and unless you get genuine Nissan parts from a Nissan dealer, the old parts are better than the auto parts ones. This means you will be introducing a faulty part into the mix and throwing away good parts.

 

Pull hose off carb and crank. Does gas spurt out?

 

Yes... fuel delivery to carb is good.

No.... find out why.

 

Pull both intake and exhaust side plug wires off and put an old plug in the end and lay it on a grounded surface like the valve cover. Crank engine over. Got spark???

 

Yes..... should start, maybe timing way out, choke not working.

Yes...... but only on the intake side.... replace the first fuse on the far left side of the fuse box

No spark on either.... Do this test on the two coil wires to the distributor cap next....

 

Yes there is spark.... distributor cap or rotor no good.

No spark... Test for 12 volts on the positive terminal of the coils, AND the Black/White wire to the distributor.

 

No 12 volts to coils and B/W wire..... ignition switch or fusible link bad

Yes, 12 volts..... module in base of distributor bad or distributor not grounded.

[81SVN20]

I agree, get expensive and unless you get genuine Nissan parts from a Nissan dealer, the old parts are better than the auto parts ones. This means you will be introducing a faulty part into the mix and throwing away good parts.

 

Pull hose off carb and crank. Does gas spurt out?

 

Yes... fuel delivery to carb is good.

No.... find out why.

 

Pull both intake and exhaust side plug wires off and put an old plug in the end and lay it on a grounded surface like the valve cover. Crank engine over. Got spark???

 

Yes..... should start, maybe timing way out, choke not working.

Yes...... but only on the intake side.... replace the first fuse on the far left side of the fuse box

No spark on either.... Do this test on the two coil wires to the distributor cap next....

 

Yes there is spark.... distributor cap or rotor no good.

No spark... Test for 12 volts on the positive terminal of the coils, AND the Black/White wire to the distributor.

 

No 12 volts to coils and B/W wire..... ignition switch or fusible link bad

Yes, 12 volts..... module in base of distributor bad or distributor not grounded.

 

Thanks Mike! I will be doing these things this weekend as I just worked on my Hardbody KA24 crankshaft seal and finished within an hour last night and work it kinda hectic right now....

Not enough time in one day! :thumbup:

[Quickshift]

One of my coils went out recently and the truck would only fire on two cylinders. it would start and rev but would only idle if you kept your foot on it. Made the truck shake something fierce. I replaced one of the coils with a 280zx coil and has run fine ever since.

[datzenmike]

Not how it works. One coil works the four intake side plugs and the other coil works the four exhaust side plugs. All four cylinders will fire with one coil mission . (but it won't run well)

 

You need 2 1/2 things for an engine to run

Spark, Gas and some compression. You have these, it will run

[81SVN20]

One of my coils went out recently and the truck would only fire on two cylinders. it would start and rev but would only idle if you kept your foot on it. Made the truck shake something fierce. I replaced one of the coils with a 280zx coil and has run fine ever since.

 

Thats good to know thanks for the reply....

[81SVN20]

Not how it works. One coil works the four intake side plugs and the other coil works the four exhaust side plugs. All four cylinders will fire with one coil mission . (but it won't run well)

 

You need 2 1/2 things for an engine to run

Spark, Gas and some compression. You have these, it will run

 

Hey Mike Im busy with work right now, I will try and tackle it this weekend and will keep you posted! thanks

[81SVN20]

Here is where I'm at I checked for fuel and the gas is up to the dot on the glass at the carb

 

I have power at both coils and the black and white wire at the distributor

 

I checked for spark no shark on either side

 

I checked for spark on coil wires going to dist. Only got spark on intake Side... Fuse is still good at the far left in fuse box

 

I replaced both coils with brand new accel coils and still only got spark from Wire to distributor on intake side

 

Should I replace the cap and rotor?

 

I'm going to make the negative ground wire from battery to body then engine brand new....

[datzenmike]

Have you done anything to the ignition system lately? Replaced or adjusted anything?

 

 

Make sure the distributor is well grounded. The module in the distributor grounds the coil and then ungrounds it to produce a spark... naturally the distributor has to be well grounded for this to work. Usually the mounting bolts will do, check they are tight and the timing adjustment screw is tight. Is the distributor loose in it's mount??? 

 

It odd that you have spark on one coil but not at the plug. Only thing between is the cap and rotor... check them for cracks, wear or damage. 

[81SVN20]

Have you done anything to the ignition system lately? Replaced or adjusted anything?

 

 

Make sure the distributor is well grounded. The module in the distributor grounds the coil and then ungrounds it to produce a spark... naturally the distributor has to be well grounded for this to work. Usually the mounting bolts will do, check they are tight and the timing adjustment screw is tight. Is the distributor loose in it's mount??? 

 

It odd that you have spark on one coil but not at the plug. Only thing between is the cap and rotor... check them for cracks, wear or damage. 

 

Have not touched anything since I bought the truck and everything is still factory minus the plug wires, seems like the previous owner mixed and matched used wires from the junkyard...

 

Mike I checked the distributor and it is mounted good I tried a test light from positive battery and touched the distributor base and light went on good no hesitation finding ground to light up...

 

How can I test the module in the distributor?  Maybe that might be bad?

 

I will be ordering new spark plug wires, cap and rotor and the spark plug are NGK and are only 2 months old...

[datzenmike]

Swap the coil wires on top of the cap. If the intakes keep working and the exhaust still not working then something is wrong with the cap or rotor.

 

If the intakes stop working and the exhaust start working then something is wrong with the exhaust coil, it's wiring or the module.

 

If you put the coil high tension wires back on the cap and swap the coils around by un-wiring them and you find the intakes stop working and the exhaust start working then the exhaust coil is bad.

 

If nothing changes then the module is suspect or possibly the wiring from the distributor to the exhaust coil.

 

These  tests should narrow down the problem. Probably the rotor or the exhaust coil but try those recommendations or it will get expensive buying parts you don't need. The ignition module from Nissan is over $300!!!