Fuel Starving? Car Trying it's best to break me?
04-05-14, 12:45 AM
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Fuel Starving? Car Trying it's best to break me?
So, I've have my project SA out for a little while, and I have been having problems that I can't seem to pinpoint.
Basically, what happens is this, the car runs EXCELLENT, great compression, carb was just rebuilt, great vacuum, everything. But every time it seems to get sufficiently warm, it starts easily, runs great, then starves for fuel.
What I thought was happening was the fuel pump was failing, so I removed the holley pump that was in the car before, and replaced it with a better Bosch pump. It didn't fix the problem.
So then I thought that it might be an electrical problem, so I triple checked all the wiring, and ran a new ground for the fuel pump. The problem still didn't fix itself ( But I did fix my 'ticking' tachometer).
I honestly have NO idea how to even approach this. I can NEVER get the car to starve out when I am working on it, and even better, when it does starve out, it starts back up again with no problems.
What I think is happening is insufficient flow to the carb, but I've literally replaced everything from the fuel pump to the carb. What would cause it to work so intermittently? On the bench, I even measured the volume, and it is pumping out the correct volume of fuel, according to the FSM. (Not that I think it would make a difference, the engine dies even on idle)
I know that it has to be a fuel supply problem, as I have replaced the points, re-wired the loom because mine was in bad shape, new coils, plugs, distributor cap, rotor. everything.
Compression is fine
Carb was rebuilt not even 100KM ago
The biggest source of frustration is that the car starts and runs fine, but then starves out. Even after it starves out, you let the ignition stay on, and it starts fine, then dies again.
I am planning on dropping the fuel tank tomorrow to check the lines in the tank for cracks or splits.
Does anyone else have any ideas on what could be causing this?
I'm tired of pushing this thing home, this is going to break me.
Car Specs:
1979, 12A, 4spd manual. Stock everything.
Basically, what happens is this, the car runs EXCELLENT, great compression, carb was just rebuilt, great vacuum, everything. But every time it seems to get sufficiently warm, it starts easily, runs great, then starves for fuel.
What I thought was happening was the fuel pump was failing, so I removed the holley pump that was in the car before, and replaced it with a better Bosch pump. It didn't fix the problem.
So then I thought that it might be an electrical problem, so I triple checked all the wiring, and ran a new ground for the fuel pump. The problem still didn't fix itself ( But I did fix my 'ticking' tachometer).
I honestly have NO idea how to even approach this. I can NEVER get the car to starve out when I am working on it, and even better, when it does starve out, it starts back up again with no problems.
What I think is happening is insufficient flow to the carb, but I've literally replaced everything from the fuel pump to the carb. What would cause it to work so intermittently? On the bench, I even measured the volume, and it is pumping out the correct volume of fuel, according to the FSM. (Not that I think it would make a difference, the engine dies even on idle)
I know that it has to be a fuel supply problem, as I have replaced the points, re-wired the loom because mine was in bad shape, new coils, plugs, distributor cap, rotor. everything.
Compression is fine
Carb was rebuilt not even 100KM ago
The biggest source of frustration is that the car starts and runs fine, but then starves out. Even after it starves out, you let the ignition stay on, and it starts fine, then dies again.
I am planning on dropping the fuel tank tomorrow to check the lines in the tank for cracks or splits.
Does anyone else have any ideas on what could be causing this?
I'm tired of pushing this thing home, this is going to break me.
Car Specs:
1979, 12A, 4spd manual. Stock everything.
04-05-14, 02:15 AM
#2
You didn't mention the fuel filter.
You didn't mention the fuel level in the site glass windows on the carb. You need to find out where the level is when it "starves out" as you say.
Another good idea is to get a wideband to confirm it goes lean enough to stall which would be an indication of fuel starvation.
You say you replaced the fuel pump ground. What about the power wire? You should add a fat power wire and use a relay triggered by the original fuel pump power wire.
Do you have a length of clear fuel line? Hook it up to your send and return lines in the engine bay. Watch for tiny bubbles. This would indicate a crack or leak allowing air to get sucked in.
By the way, no need to drop the tank if you aren't getting gas fumes back there. But it's your car. Do what you're gonna do.
You didn't mention the fuel level in the site glass windows on the carb. You need to find out where the level is when it "starves out" as you say.
Another good idea is to get a wideband to confirm it goes lean enough to stall which would be an indication of fuel starvation.
You say you replaced the fuel pump ground. What about the power wire? You should add a fat power wire and use a relay triggered by the original fuel pump power wire.
Do you have a length of clear fuel line? Hook it up to your send and return lines in the engine bay. Watch for tiny bubbles. This would indicate a crack or leak allowing air to get sucked in.
By the way, no need to drop the tank if you aren't getting gas fumes back there. But it's your car. Do what you're gonna do.
04-05-14, 03:47 AM
#3
Jeff is on it-
Sounds like classic fuel starvation. And the fact it starts up and runs after sitting makes me think your fuel lines - more likely the TANK, is plugging up. Classically the engine runs, sucks fuel AND debris to the fuel outlet in the tank, plugs it, it stalls, the debris drifts away to free up the fuel flow, you start it, and it happens again...
My 80 did this and altho changing the fuel filter helped, it ultimately re-plugs-up from the gunge from the Tank. Only solution is pull the tank, get it chem-dunked at a reputable Rad shop, then RE-LINE it with a known product like POR15 (.com)'s fuel tank liquid sealer kit (about $30).
And, long term, a great idea is to be sure the RX always has a FULL tank (I add Stabil fuel stabilizer) when its put in storage. Its the air-space in the partially-full tanks that allow condensation to collect and create rust = more junk to flake off into the fuel. Again.
NOTE the 80 SA does NOT have a fuel drain plug, so I pulled the sender unit (driver side rear wheel well, behind the plastic cover panel) and drained it from there. You will need to be sure to have a sender gasket! You do NOT want to be dropping a tank with much gas in it!! Impossible to balance with fluid sloshing around as you pull it. Ask me how I found out....
Best of luck - actually a pretty straight forward fix.
Stu Aull
80GS
Alaska
Sounds like classic fuel starvation. And the fact it starts up and runs after sitting makes me think your fuel lines - more likely the TANK, is plugging up. Classically the engine runs, sucks fuel AND debris to the fuel outlet in the tank, plugs it, it stalls, the debris drifts away to free up the fuel flow, you start it, and it happens again...
My 80 did this and altho changing the fuel filter helped, it ultimately re-plugs-up from the gunge from the Tank. Only solution is pull the tank, get it chem-dunked at a reputable Rad shop, then RE-LINE it with a known product like POR15 (.com)'s fuel tank liquid sealer kit (about $30).
And, long term, a great idea is to be sure the RX always has a FULL tank (I add Stabil fuel stabilizer) when its put in storage. Its the air-space in the partially-full tanks that allow condensation to collect and create rust = more junk to flake off into the fuel. Again.
NOTE the 80 SA does NOT have a fuel drain plug, so I pulled the sender unit (driver side rear wheel well, behind the plastic cover panel) and drained it from there. You will need to be sure to have a sender gasket! You do NOT want to be dropping a tank with much gas in it!! Impossible to balance with fluid sloshing around as you pull it. Ask me how I found out....
Best of luck - actually a pretty straight forward fix.
Stu Aull
80GS
Alaska
04-05-14, 06:17 AM
#4
I was where you are a year ago. Do as the Alaskan suggests. You can replace the fuel strainer at the pickup with a modern sock, just go to the parts store and sort through the selection. And replace all the fuel lines while you're there. It's easier than you think, and the reward is great.
04-05-14, 10:11 AM
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You didn't mention the fuel filter.
You didn't mention the fuel level in the site glass windows on the carb. You need to find out where the level is when it "starves out" as you say.
Another good idea is to get a wideband to confirm it goes lean enough to stall which would be an indication of fuel starvation.
You say you replaced the fuel pump ground. What about the power wire? You should add a fat power wire and use a relay triggered by the original fuel pump power wire.
Do you have a length of clear fuel line? Hook it up to your send and return lines in the engine bay. Watch for tiny bubbles. This would indicate a crack or leak allowing air to get sucked in.
You didn't mention the fuel level in the site glass windows on the carb. You need to find out where the level is when it "starves out" as you say.
Another good idea is to get a wideband to confirm it goes lean enough to stall which would be an indication of fuel starvation.
You say you replaced the fuel pump ground. What about the power wire? You should add a fat power wire and use a relay triggered by the original fuel pump power wire.
Do you have a length of clear fuel line? Hook it up to your send and return lines in the engine bay. Watch for tiny bubbles. This would indicate a crack or leak allowing air to get sucked in.
2) As I said, I can't get the problem to happen on the bench, it will only happen when I am AT LEAST 1Km away from my house. Just close enough to push it.
3) Any Suggestions, or just your average store model?
4) Replaced the power wire as well. The nozzle that had the car before me had spliced his amp into that line, so I ran a new line all the way back. The power system must be fine, because I've driven with a multimeter hooked up and the power stays stable, even when the car dies.
5)I do get a few little bubbles, but I assumed it was normal.
Only solution is pull the tank, get it chem-dunked at a reputable Rad shop, then RE-LINE
I was planning on doing this.
04-05-14, 07:14 PM
#7
Droped the tank on my first SA shortly after purchase because of the same issues. Replaced all fuel filters and lines. Starving durring load, but bench is fine.
Flushing the tank solved all my issues.
Really not hard to flush out the tank, and it gives you some time to check on possible rusty/worn need re-undercoating parts.
Flushing the tank solved all my issues.
Really not hard to flush out the tank, and it gives you some time to check on possible rusty/worn need re-undercoating parts.
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04-06-14, 08:47 AM
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am having this issue now also but almost fixed.my air jets were clogedi bet the iner is also mine starves or bogs at 5000 rpm or when i open it all the way than after several sec it picks up n goes.drove fine the other night.went to run it yesterday and now its not firing off its almost running.so i am messing with timming.but tdc and diz are lined up i am thiunking theres like 6options for tdc?what is true tdc to #1 rotordoes it fire 3 times per rotor?and why will it start and run fine when i switch l1 and l2 wires? strange motor
04-06-14, 01:32 PM
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am having this issue now also but almost fixed.my air jets were clogedi bet the iner is also mine starves or bogs at 5000 rpm or when i open it all the way than after several sec it picks up n goes.drove fine the other night.went to run it yesterday and now its not firing off its almost running.so i am messing with timming.but tdc and diz are lined up i am thiunking theres like 6options for tdc?what is true tdc to #1 rotordoes it fire 3 times per rotor?and why will it start and run fine when i switch l1 and l2 wires? strange motor
04-24-14, 11:19 PM
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Sorry for the bump, but we had some nice weather today, and I spent all day fixing this problem.
Firstly, I dropped the tank, and checked with my borescope, the tank was beautiful inside, no visible rust. Regardless, I flushed it, and filled up with some fresh stuff.
Slipped the tank back in, then I hooked up a multimeter to the fuel pump so that I could monitor the voltage while driving. I took it for a drive and it died again, but the voltage was stable across the range that it was supposed to stay.
So I knew that it had to be a fuel line problem. I started at the carby and worked backwards. disconnecting lines and switching the pump on to check if it was flowing properly. Eventually I tracked the problem back, and it was to a spot that I didn't expect.
The Fuel Cutoff Valve. This valve is a little ball that basically shuts the gas off when the car rolls, it basically exists to stop the car from exploding into flames during an accident.
What was happening on my valve, was that the car would bump the valve, and then the pressure of the pump would hold the ball into a cutoff position, the only way to reset it was to let the pressure bleed back through the pump and filter.
Morale of the story? Check your FCV if you have a problem like this.
Firstly, I dropped the tank, and checked with my borescope, the tank was beautiful inside, no visible rust. Regardless, I flushed it, and filled up with some fresh stuff.
Slipped the tank back in, then I hooked up a multimeter to the fuel pump so that I could monitor the voltage while driving. I took it for a drive and it died again, but the voltage was stable across the range that it was supposed to stay.
So I knew that it had to be a fuel line problem. I started at the carby and worked backwards. disconnecting lines and switching the pump on to check if it was flowing properly. Eventually I tracked the problem back, and it was to a spot that I didn't expect.
The Fuel Cutoff Valve. This valve is a little ball that basically shuts the gas off when the car rolls, it basically exists to stop the car from exploding into flames during an accident.
What was happening on my valve, was that the car would bump the valve, and then the pressure of the pump would hold the ball into a cutoff position, the only way to reset it was to let the pressure bleed back through the pump and filter.
Morale of the story? Check your FCV if you have a problem like this.
04-25-14, 08:43 AM
#14
carb whisperer
Sorry for the bump, but we had some nice weather today, and I spent all day fixing this problem.
Firstly, I dropped the tank, and checked with my borescope, the tank was beautiful inside, no visible rust. Regardless, I flushed it, and filled up with some fresh stuff.
Slipped the tank back in, then I hooked up a multimeter to the fuel pump so that I could monitor the voltage while driving. I took it for a drive and it died again, but the voltage was stable across the range that it was supposed to stay.
So I knew that it had to be a fuel line problem. I started at the carby and worked backwards. disconnecting lines and switching the pump on to check if it was flowing properly. Eventually I tracked the problem back, and it was to a spot that I didn't expect.
The Fuel Cutoff Valve. This valve is a little ball that basically shuts the gas off when the car rolls, it basically exists to stop the car from exploding into flames during an accident.
What was happening on my valve, was that the car would bump the valve, and then the pressure of the pump would hold the ball into a cutoff position, the only way to reset it was to let the pressure bleed back through the pump and filter.
Morale of the story? Check your FCV if you have a problem like this.
Firstly, I dropped the tank, and checked with my borescope, the tank was beautiful inside, no visible rust. Regardless, I flushed it, and filled up with some fresh stuff.
Slipped the tank back in, then I hooked up a multimeter to the fuel pump so that I could monitor the voltage while driving. I took it for a drive and it died again, but the voltage was stable across the range that it was supposed to stay.
So I knew that it had to be a fuel line problem. I started at the carby and worked backwards. disconnecting lines and switching the pump on to check if it was flowing properly. Eventually I tracked the problem back, and it was to a spot that I didn't expect.
The Fuel Cutoff Valve. This valve is a little ball that basically shuts the gas off when the car rolls, it basically exists to stop the car from exploding into flames during an accident.
What was happening on my valve, was that the car would bump the valve, and then the pressure of the pump would hold the ball into a cutoff position, the only way to reset it was to let the pressure bleed back through the pump and filter.
Morale of the story? Check your FCV if you have a problem like this.
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