Printable View
I have a 1995 Mighty Max with a redone head and a new gasket. The distributor must be fully advanced for the truck to start and idle. As soon as throttle is applied it bogs down and will shut down. I do not know where to start looking. Please advise...
Hi, i would start by looking at the distrubutor and vac lines. are all the lines attached where they need to be?
I would then look at the distrubutor, and check that it has gone back, in the correct position (it could be a few teeth out). Can check that by rotating engine to top dead centre on the compression stroke on piston 1(take the plug out, put your thumb over the plug hole and feel for compression, then use a long screwdriver to see when the piston reaches the top of its travel)
At tdc the distributor rotor should be pointing at #1 cylinder plug lead on the distributor cap
Your distributor looks like it's installed 'incorrectly'. If you bump the distributor a tooth forward (remove the distributor and turn it clockwise 1 spline) and it will only fire when the adjustment is fully retarded you have an issue I have run into before and can be remedied by changing the firing order. Remove the distributor and install it 180 degrees out (rotor button facing #4 lead on the distributor cap) and swap the #1 lead location to #4, then swap #2 location to #3. I'm not 100% sure why it happens but for some reason after head work the distributor ends out being 1/2 a tooth out. If the test where you have removed the distributor and bumped it a tooth and adjusted the advance didn't yeild a result the issue is somewhere else (maybe faulty vac advance unit on the distributor or as suggested vac lines)
I pulled everything back down and made sure the timing marks were set correct. The look to be correct but then again I am looking down at an angle with limited room for my big head. They are close! I then pulled the distributor and found the mark on the gear and the housing and lined them up. At that time I marked the rotor button position. Then I reinstalled the distributor and the truck will start up and does idle better. I tried to set the timing by putting the computer in timing mode with a jumper and used the light. I never saw my crank mark in the strobe and it is painted white. Is this bad? The motor seems to run better with the computer in timing mode. I did drive it to the gas station for some fresh gas and noticed spark knock or chattering at 35mph in 3rd gear.
you are still too advanced on the timing - sound like you are still one tooth off on the distributor.
If you don't have the timing mark within the degree markers on the cover, it's way out. Put it into diagnostic mode and dial it back to the factory recommended tune. If you want to find out if there is any untapped performance in the tune, get someone to hold the engine rpm @ 2000 and gently swing the distributor back and forth until you notice the rpm's jump by themselves, then retard the timing just a touch. Lock the distributor up and take it for a drive - take note of engine response and how much further the engine power band has extended. The factory tune nerfs these engines and it is more noticeable with OBD I engine management.
Is the dot on the distributor gear and the nub on the bottom of the distributor housing what I use to line up the rotor button for #1 cylinder? I removed the timing gear cover, the number 1 plug and turned the crank with a breaker bar to watch my marks line up. When the mark on the crank pulley stopped at the T on the degree marking my cam mark was on the money with the nub on the head. I then pulled the distributor cap and it appears to be on the #1 plug wire. That would be the bottom one closest to the front of the truck. The truck cranked over like normal then started struggling to crank over like it was compressing air. I still do not see the crank shaft pulley timing mark with the timing light. I rotated the distributor both ways and still no mark. Will I have to start pulling the distributor in and out and just rotating it 1 tooth at a time until I get results?
To me it sounds like you are setting the timing up correctly. If you were able to get it to fire the first time with full advance then the coil and ICM in the distributor seem to be working. Have you tried bumping the distributor a tooth forward and retarding the timing to test if you are getting any sign of spark? You will only get a small scope of movement 1 tooth forward or back before it refuses to fire completely. Mark your leads and try swapping the firing order as I suggested earlier just to test it out. Hopefully you will get results.
Thanks Guys, I will be back on this project Tuesday. Gotta work of you wanna play. Lol
Finally got the distributor set right!
So I set the timing with the computer in timing mode. When I unhooked the jumper the timing mark was not in the range I set it. Why is this?