7MGTE 1989 Won't Start

[jkendall86]

Thanks jetjock....I have been checking on this on and off all day today.....I took out each plug to check for gap. They are NGK and I read that this model should be gapped to .32, so I did. I then plugged them all into the wires and tried to see if I could see any spark on them....alas, I did not. I am certain that I have fuel going through the rail, but I do not have a noid, so I am going to get one tomorrow to see if the injectors are pulsing. I am also going to get a spark tester, the one with the light, to better test the coil packs. They tested with good resistance. I am fairly certain that the CPS is connected correctly and that the Timing is set correctly (done this many times and all four points:cps, crank and both cam gears: are aligned). While i did see the timing light "blink" while cranking, I am not 100% certain it is firing or that the injectors are pulsing....

This is all very annoying.....Running one day, then not the next.

 

[jkendall86]

UPDATE.....got spark on all 6, tested with a light....since I had everything off, decided to do compression test, 50-70 on all 6. 7M just took a huge dump!

 

[Nick M]

That said, properly done solder is better than crimping with cheap hardware store terminals and tooling. And whatever you do stay away from IDC connectors...

Toyota splice

 

[Nick M]

decided to do compression test, 50-70 on all 6. 7M just took a huge dump!

Not likely. You would have very poor performance at just 110 psi. It doesn't happen fast without catastrophic failure. And that is often not all of the cylinders. Make sure your cylinder walls are not soaked in fuel. When they are, compression drops across the board. It will sound like it has no compression.

 

[jkendall86]

Early on when i was lining up all the marks to put in the CPS, the crank turned very easy...like it didn't have much compression. I am sure the cylinders have a lot of fuel in there as i have tried many times to start it...i have gotten a "poof" a couple of times with the 300 pipe off. I took off the cam covers to get a look at the cams to make sure they were ok...and they are.

 

[3p141592654]

A jumped belt or other timing problem can result in across the board loss of compression.

 

[jkendall86]

I am hoping for that...but when I originally lookwd , the can gears were straight up and the crank was at 0

 

[jkendall86]

Im looking for the "other timing problems".....got ideas?

 

[3p141592654]

Sometimes the crank pulley can slip on its internal rubber dampener making the 0 mark no longer 0. You can check that with a chopstick stuck in the spark plug hole.

 

[super51fan]

^^^ Good idea to verify. Btw fuel fouled plugs will not fire. If you have checked all the above and timing and cps is installed properly you should also install fresh "new " sparkplugs. Some disagree but a fuel fouled plug that is dry still will not fire properly. IMO

Cylinders "washed out" with fuel will have low compression also. After You have verified correct timing I would pull plugs out and add a tablespoon of oil in each cylinder. Then pull EFI fuse and crank engine over for 30 seconds with plugs out. Then install you new plugs. IMO

 

[jkendall86]

After further review.....I finally got the noid light....no light...checked voltage on the plug while disconnected...it has power to one side, but not the other....I swapped my ECU and got the same results....so it appears that there is a wiring issue somewhere. I swapped out the Injector resistor, same result. I checked for power to the resistor, it has 12 volts. WOW.....

 

[3p141592654]

Power on one side, none on the other is normal? The ECU grounds the -ve side of the injector to make it fire. The +ve side is always hot.

 

[jetjock]

Now I'm wondering if he held the throttle open during the compression check...

 

[jkendall86]

The answer is no....would that make a difference because compression is done when the valves are closed

 

[super51fan]

I would wiggle and pull and push on your wire harness by the #6 intake runner, gently maybe an inch or so each way. They seem to develop opens in that area. I bet you have a open circuit from injectors to ecu or ecu to ground "B" on intake manifold. I bet if you move harness around slightly it may start and run and then can confirm and repair wiring.

Most people don't open throttle to do a proper compression test.

 

[Nick M]

The answer is no....would that make a difference because compression is done when the valves are closed

It allows air into the engine. If the engine is cold and STA (cranking) is active, a bunch of extra fuel is injected.

Click here.

 

[suprarx7nut]

The answer is no....would that make a difference because compression is done when the valves are closed

I've done compression checks with the throttle closed and open and haven't noticed a huge difference. Not nearly enough to give you 70 psi or whatever you said. It'll make a difference, but not that much. I know from first hand experience on multiple 7Ms.

 

[jkendall86]

PI....Are you saying your not sure with that question mark, or should it not have power on both sides???

I am frustrated at the moment with this...part of me says the compression is way to low and I should pull and rebuild, but then I would not have a solution to the no start issue and may be looking at further frustration once I install the engine again. I am trying to fix all the gremlins to verify that the engine is truly fubar....the hardest part is tracing all the small issues...right now its the injectors not firing....I get power to one side and then none to the other and the noid light does not pulse....

 

[jetjock]

...Most people don't open throttle to do a proper compression test.

Then they're doing it wrong. Doing so is automotive repair 101. Basic stuff.

 

[jkendall86]

OK....so I should have done the compression test with the throttle open....I will remember that in the future, but my numbers were so low, that I cant imagine opening the throttle would have increased numbers from 50-90 points....

My main issue now is to look at why I have no injector pulse using a noid light. I read the entire thread by backyardmechanic1, it seemed like his problem was very similar to mine, but I do not think there was a real solution. What I got out of it was to check all the grounds....been there, done that...Twice. Grounds under intake, removed and replaced. Battery terminal ground to block, removed and replaced. Battery terminals cleaned and tightened. Battery fully charged. Ground strap on rear engine hook, removed and tightened. Ground on coil packs, removed and replaced. Ground on the ignitor added and tight. Ground on transmission, removed and replaced. Ecu swapped and tightened in place. I have replaced Ignitor, main relay, injector relay, fuel pump relay and ECU. I have checked, pulled and replaced every fuse in the engine and drivers kick pane.....NOW????