91 GT won't start

[mnatts6642]

First off, thanks for everyone on here for so much info. Without this forum I would have really been lost. I bought a 91 GT and a 94 GTX off CL. Both were neglected and rough, but had promise. From the info on here between the posts and articles from everyone, I pulled the carbs from both being sure I didn't disrupt the rotary valves, rebuilt them, replaced all the gray fuel lines with new black fuel line, put brand new fuel baffles in both (I am also installing a fuel gauge and oil sensor in the 91 so that's why it has a baffle instead of the fuel lines into the tank), brand new fuel selectors, and bypassed the fuel filters in the hulls with in-line fuel filters. I have brand new spark plugs in both, BR7ES in the 91 and BR8ES in the 94, gapped correctly. Brand new oil in both. Brand new batteries. Finally got everything installed and put back together, batteries hooked up, and the 94 fired right up. It will now turn over and start with just a tap of the button, which is great (I have an oil leak from the oil line at the bottom of the engine, but thats a separate issue.) I moved on to the 91, and it will not start. I verified the fuel pump is pulling fuel and the pulse is working, because I can see the fuel flowing into the filter when I hit the start button. So I'm stumped. I think I might not be getting spark at the plugs, but not sure, and since I'm new to these, I don't know how to check and cannot figure out how to replace the spark plug wires, if there even is a way. Any help is appreciated, and I'll give any suggestion from you guys a shot. Thanks again for all the info up to this point.

 

[clmboating]

First off, thanks for everyone on here for so much info. Without this forum I would have really been lost. I bought a 91 GT and a 94 GTX off CL. Both were neglected and rough, but had promise. From the info on here between the posts and articles from everyone, I pulled the carbs from both being sure I didn't disrupt the rotary valves, rebuilt them, replaced all the gray fuel lines with new black fuel line, put brand new fuel baffles in both (I am also installing a fuel gauge and oil sensor in the 91 so that's why it has a baffle instead of the fuel lines into the tank), brand new fuel selectors, and bypassed the fuel filters in the hulls with in-line fuel filters. I have brand new spark plugs in both, BR7ES in the 91 and BR8ES in the 94, gapped correctly. Brand new oil in both. Brand new batteries. Finally got everything installed and put back together, batteries hooked up, and the 94 fired right up. It will now turn over and start with just a tap of the button, which is great (I have an oil leak from the oil line at the bottom of the engine, but thats a separate issue.) I moved on to the 91, and it will not start. I verified the fuel pump is pulling fuel and the pulse is working, because I can see the fuel flowing into the filter when I hit the start button. So I'm stumped. I think I might not be getting spark at the plugs, but not sure, and since I'm new to these, I don't know how to check and cannot figure out how to replace the spark plug wires, if there even is a way. Any help is appreciated, and I'll give any suggestion from you guys a shot. Thanks again for all the info up to this point.

Sometimes the spark plug wires can get gunked up, and usually can be solved by using a pencil eraser on it. You're getting 2 beeps, correct?

 

[mnatts6642]

no beeps. 91, so doesn't have DESS

 

[mnatts6642]

Just tried cleaning the contacts and also snipped about 1/2" from the plug wires and re-installed the boot. Still no dice.

 

[Coastiejoe]

Two things. Buy a spark tester as this will answer the question, and, put some mixed oil/gas down the carb. Will it start then?


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[mnatts6642]

Just tried squirting gas into the carbs. Didn't work, no change in sound.

 

[Coastiejoe]

If you can't test for spark, if you do a compression test that will help as well.

Sounding like spark though.


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[Mickirig1]

See if you can borrow an induction timing light. Hook it up and see if you are get spark signal to wires. Have the flame arrestor on the carb if you put gas down it. Takes a table spoon of gas to make it fire up. Sometimes it needs that kick to get them flowing gas for the first time. Pull choke fully closed when you try to start. It causes more vacuum to draw gas into carb.

 

[mnatts6642]

Will try the timing light and compression test. Had choke closed when trying after squirting gas into carb. Going to pull the carbs again tomorrow and open them up to see if I missed anything on this set. I did pull the plugs and place a rag over the holes and turned over the engine, and it was pushing air out of the holes, so I know its not seized, but it can still do that and have low compression, right? So the test is definitely in order. Thanks for the help and suggestions everyone.

 

[Coastiejoe]

Yes, could still be low compression.

Don't open the carbs until you know if you have spark. Just don't want to waste your time unnecessary.


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[howie099]

yellow engine has the all the electronics in the front engine cover. I would download the manual and start testing all of that out. Also make sure your your compression is ok. If compression is bad why go forward. You usually just need to ground the spark plug on the engine exhaust or something like that to see the spark.

 

[mnatts6642]

Ok, tested spark and compression. Spark is good. Compression is not. 120 at both cylinders. So, I'm looking at top end rebuild?

 

[howie099]

yes you would need a top-end but that old go for the whole engine, but I would make sure you have a good tester. Test the 94 GTX to see if that one is in spec.

 

[mnatts6642]

It is, I checked it just to be sure after I checked the 91. 150 both cylinders. Started right up again after replacing plugs and tapping the button. So I'm happy about that. So am I gonna be better off getting an sbt rebuilt or just rebuilding the top end? I don't know the exact history of the engine and that worries me