I have a roller 302 with a t5 in my project Mustang. It was running fine for the month I got it running and the couple of weeks I drove it, although it did run a little rich. One night I kind of got on it then the car started stumbling then backfired and I had to keep giving gas and it kept dying when I put it in gear. When I got home I did a compression test which was fine and I started it the next day it ran "okay" but sounded kind of off and when it gets put in gear it dies. I tried to start it the next couple of days and it would start run rough and sound like it wasn't getting gas then die unless you gave it gas, and wouldn't start again unless you let it sit for a while, and it would backfire sometimes through the carb when I attempted to start it. I pulled off the timing cover just to verify everything was fine and the timing marks lined up and they did, and also checked the distributor to check that it was at TDC and it was. Then I decided to just re install the distributor (which is a new hei unit) and re time the car. After I re installed at TDC and set the timing and it ran fine for a while and even even turned it off and started it again to make sure. Then it just started idling rough and died again. When I started it again it idled rough then I would loosen the distributor to move it then it got a little better then just died again. I really don't know what could be wrong now I have a new timing gear and chain so there not worn. The car keeps on losing timing and I don't know why.
Have no idea why car won't run right
- Thread starter sj9ers
- Start date
woodsnake
15 Year Member
I didn't really read the entire first post, but have you checked for electrical issues? Grounding, battery, alternator, the wires going from battery to alternator, and from battery/alternator to chassis?
I only bring this up because I've been dealing with a misfire in my car, and so far everythings pointing to an electrical issue. Not sure about your car, but for the 94/95 ECU's, they're real picky when it comes to electrical/power issues.
Good luck!
I only bring this up because I've been dealing with a misfire in my car, and so far everythings pointing to an electrical issue. Not sure about your car, but for the 94/95 ECU's, they're real picky when it comes to electrical/power issues.
Good luck!
It has a carb not fuel injected. Well when I had the car running good there was a vacuum gauge plugged into the car and it was holding vacuum between 18 and 20 for the 15 min or so it was running good but when it started to idle rough and die the gauge went down to around 5 or 10. When it did idle however it was idling pretty fast and wouldn't go down that much even after I back off the idle screw all the way. Is that a symptom of a vacuum leak? And if it is a vacuum leak would it run as "well" as it did for the 15 min and then just suddenly run rough and die like that?
Thanks
Thanks
I re installed the distributor and re timed and it was running fine. So I don't think thats the issue.
Platonic Solid
Founding Member
woodsnake
15 Year Member
Sounds like a massive vacuum leak. Get a can of carb cleaner and try to keep it running long enough to spray around the manifold, carb, etc....
jcode68
Active Member
This sounds like the symptoms of a vaccum leak, although not too sure about why it would run ok for 15 minutes. Perhaps with the choke still on, it would over compensate and appear to run ok until the choke came off. Get some carb cleaner and with the engine running, spray it around the base of the carb, the intake manifold where it seats against the block and heads. If the engine RPM changes while spraying, you have found your vaccum leak. If you have power brakes, be sure to check for leaks around the booster check valve etc. Should be an easy fix once you locate the issue.
it does sound like a vacuum leak. if your engine has a thermostatically controlled vacuum switch, you will find it at the engine in the coolant cross over passage or in the thermostat housing, that would allow the engine to run normally until it warmed up and then the vacuum leak would surface. probably in one of the hoses.
woodsnake
15 Year Member
In a word.....YUP!
You have un-metered air where the carb and intake manifold meet. How can it be expected to run like that??
I think I would have rather had the engine running to determine the leak, rather than pressurizing the intake, but I guess it works...
Do you have a spare carb that you know is good to test the throttle shaft?
You have un-metered air where the carb and intake manifold meet. How can it be expected to run like that??
I think I would have rather had the engine running to determine the leak, rather than pressurizing the intake, but I guess it works...
Do you have a spare carb that you know is good to test the throttle shaft?
Actually it was the secondary throttle shaft that was leaking not the primary one. I would have like to have the car running to test it but I can't even to get it to start and if it does it's only a couple of seconds and really really rough. When I did the pressurized test I could only find that leak and nothing else. I tried this method to see if there was an internal one How to check for an Internal Vacuum Leak - The Rice Haters Club and I got vacuum pressure when the engine was cranking between 7 and 10. Is there any other way to check for an internal vacuum leak?
Also if it's not a vacuum leak could it be my carb? I know the car always idled fast and it would barely go down even if I backed the idle screw all the way. And when the carb was on the original 302 when I got the car last September it would die in gear if you gave it gas so I'm betting its the carb. And why would the car actually run okay when I re installed the distributor?
Also if it's not a vacuum leak could it be my carb? I know the car always idled fast and it would barely go down even if I backed the idle screw all the way. And when the carb was on the original 302 when I got the car last September it would die in gear if you gave it gas so I'm betting its the carb. And why would the car actually run okay when I re installed the distributor?
I didn't read the entire first post, because it was too difficult to read . . . though there was punctuation, it looked like a very long run-on sentence.
Don't take this wrong, but it might be a good idea to place a line in between your sentences to make your posts easier to read.
Nearly everyone who has responded feels that it sound like you have a vacuum leak, and that's possible, but it's also possible that you have low compression on one of the cylinders--I have seen that very issue before.
I would recommend running a compression check . . .
Don't take this wrong, but it might be a good idea to place a line in between your sentences to make your posts easier to read.
Nearly everyone who has responded feels that it sound like you have a vacuum leak, and that's possible, but it's also possible that you have low compression on one of the cylinders--I have seen that very issue before.
I would recommend running a compression check . . .
RGS0907
New Member
He did have punctuation and in his fourth sentence, he talked about running a compression check.. Adding more spaces between paragraphs isn’t a bad idea, but I’d give the guy a break.
I didn't say he didn't have punctuation (please re-read my post), I said that I didn't read through it because it was too difficult to read due to the fact that it looked like just a long run on sentence.
I wasn't trying to give him a hard time, either, I was just offering constructive criticism based on the difficulty I had (and possibly others as well) in reading the original post.
And yes, I didn't see the part about the compression check because I didn't get through the original post . . .
woodsnake
15 Year Member
This is starting to look that that last thread that ended up being the firing order...
It needs three things to run. Air, fuel, and spark. If you have an HEI ignition, Double check your connections.
I still think you have another vacuum leak some where. If it is a new timing gear set, then what else could it be?
Back to basics. Loose wires, firing order, check the distributor for a loose connection under the cap.
Can you borrow a carb to test with?
When I went to school the phrase was "symptom to system, component to cause".
Qualify the ignition, then get back to the carb. If the carb is good then get a hammer.....
It needs three things to run. Air, fuel, and spark. If you have an HEI ignition, Double check your connections.
I still think you have another vacuum leak some where. If it is a new timing gear set, then what else could it be?
Back to basics. Loose wires, firing order, check the distributor for a loose connection under the cap.
Can you borrow a carb to test with?
When I went to school the phrase was "symptom to system, component to cause".
Qualify the ignition, then get back to the carb. If the carb is good then get a hammer.....
70Mach351c
Member
I fell victim to that...
A, ahem, 'gremlin' (not an AMC) switched up a couple of plug wires on the distributor. 1, 4 and maybe 6. Dunno.. but my car was doing the exact thing you're describing. For me, I thought the new pulleys I had installed were throwing the engine balance way off, it was shuddering badly, then popping and backfiring.
BE CAREFUL about the wiring order. When I went for an outside reference for firing order, I found that there is one for 351, and another for every other V8. Unfortunately, at one point the Chilton manual had it wrong. I have that manual. I spent another hour online making sure it was wrong. Mine wasn't wired to the wrong order entirely, I had pulled the cap aside for something and probably did it to myself.
I checked the firing order and plug wires over and over just to make sure and and they were correct. I even re installed the distributor with a new number one spark plug on the cap for the firing order and it fired right up for a while but idled fast and died after 15 or so minutes and wouldn't start again.
The only thing I can think of now is the carburetor, but I don't have an extra one to throw on, and the car will hardly start now.
The only thing I can think of now is the carburetor, but I don't have an extra one to throw on, and the car will hardly start now.
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