Crankshaft Position Sensor (1 Viewer)

[emac]

No chance that electric fuel pump is crapping out? How is it wired?

 

[FJ4013]

I had a car do this to me and it ended up being a pin hole in the fuel line it was big enough to draw air in but not leak out.

I replaced all of the fuel lines in the engine bay about 10 months ago. I have not touched the fuel lines running along the base of the frame into the gas tank if that is what you are thinking.

No chance that electric fuel pump is crapping out? How is it wired?

That was the very first thing I replaced as I thought perhaps it was a bad pump. The new pump has been running great. I'm not following you when you ask how it's wired. It sits just below the fuel tank as close as it can get. I have a fuel filter between the tank and the pump and another inline filter after the pump all in the same area as the fuel pump. I also have a ground wire running to the frame.

 

[emac]

The fuel pump is not stock, so someone ran wires to it. Just wondering where the power is coming from. But, if you say you are pumping fuel into the carb when the motor quits, then fuel delivery isnt an issue. You also say you are getting spark, when the engine quits. Something just isnt adding up. I find it very hard to believe that you are in fact getting fuel and spark when the motor quits, but after some time it just fires right up. Very, very odd. Nothing personal, but I am questioning your testing.

I would suggest you grab a friend and some testing tools. When it quits, video how you test for spark and fuel delivery. Or at least throw a little fuel in the carb and video it trying to start. Thats about all I can add without being hands on.

 

[pb4ugo]

I agree with emac, the OP's descriptions, symptoms and testing are very confusing. Like, It cranks slowly, then cranks over. Does this mean it started? In the pics it appears that the electrical connections need to be cleaned especially when trying to diagnose a possible electrical problem, then we hear about about a loose wire. By cleaning the connections he might find a problem. What I see in the black melted wire pic is corrosion starting under the insulation.

What's the condition of the pos and neg battery cables? Is the pertronix red wire getting 12 volts? Is the coil internally resisted? If it is, is it getting 12 volts to the + side of the coil. Did you have these same symptoms, of cutting out, b4 the petronix was installed? I fought a pertronix problem for a couple of months last year on our boat. The symptoms were identical to the OP's. It would run for a while sputter and die. At first, we were sure we had a fuel problem. I'd fool with the carb and then it would start and run for a while. With me messing with the carb, it allowed time for the petronix unit to cool down. One time, It started and idled fine, but if we applied more fuel it would sputter and try to die, till we backed off the throttle. I was still sure it was a fuel problem so the next time out i brought another carb to swap. 30 mins into the ride the motor quit, we were getting ready to make the carb swap and noticed it was getting plenty of fuel, so we checked spark and had none. We pulled the petronix unit and reinstalled the points plate, and all is still good. I'd clean all your connections then start isolating various components of the ignition system. 1st if it has an internal resisted coil, disconnect the 40's pos wires off of the + side of the coil and supply 12 volts from the battery and start it and drive it. If the problems go away then its the petronix unit. Remember, to turn the engine off you'll have to pull that jumper bat wire off the coil. If the problem still exists, Id probably go to the next easiest component to isolate, the ING switch. Disconnect the switch's plug from the harness, locate the bat wire, ING wire, and start wire, in the 40's plug and make a pig tail so you can hot wire it and drive it. etc. There may be 2 separate issues going on, 1 slow cranking and the other stalling/cutting out.

 

[vpatsears]

I had something similar with an electric fuel pump. Once the pump got warm it would shut off. Check to see if the pump is still vibrating after the motor cuts out. Should be able to feel it by placing your hand on it.

 

[emac]

I agree with emac, the OP's descriptions, symptoms and testing are very confusing. Like, It cranks slowly, then cranks over. Does this mean it started? In the pics it appears that the electrical connections need to be cleaned especially when trying to diagnose a possible electrical problem, then we hear about about a loose wire. By cleaning the connections he might find a problem. What I see in the black melted wire pic is corrosion starting under the insulation.

What's the condition of the pos and neg battery cables? Is the pertronix red wire getting 12 volts? Is the coil internally resisted? If it is, is it getting 12 volts to the + side of the coil. Did you have these same symptoms, of cutting out, b4 the petronix was installed? I fought a pertronix problem for a couple of months last year on our boat. The symptoms were identical to the OP's. It would run for a while sputter and die. At first, we were sure we had a fuel problem. I'd fool with the carb and then it would start and run for a while. With me messing with the carb, it allowed time for the petronix unit to cool down. One time, It started and idled fine, but if we applied more fuel it would sputter and try to die, till we backed off the throttle. I was still sure it was a fuel problem so the next time out i brought another carb to swap. 30 mins into the ride the motor quit, we were getting ready to make the carb swap and noticed it was getting plenty of fuel, so we checked spark and had none. We pulled the petronix unit and reinstalled the points plate, and all is still good. I'd clean all your connections then start isolating various components of the ignition system. 1st if it has an internal resisted coil, disconnect the 40's pos wires off of the + side of the coil and supply 12 volts from the battery and start it and drive it. If the problems go away then its the petronix unit. Remember, to turn the engine off you'll have to pull that jumper bat wire off the coil. If the problem still exists, Id probably go to the next easiest component to isolate, the ING switch. Disconnect the switch's plug from the harness, locate the bat wire, ING wire, and start wire, in the 40's plug and make a pig tail so you can hot wire it and drive it. etc. There may be 2 separate issues going on, 1 slow cranking and the other stalling/cutting out.

I had a similar 351W boat issue and it turned out to be cheap chinese coils (sold as PCM replacements) that were not designed to be mounted sideways like the OEM . Went to epoxy, off road style and it worked great.

 

[hobbes]

I have a Weber. JimC is reworking an OEM I’m converting to as I’m swapping engines. Back in my hot AZ days, I had a hard time with vapor lock with the Weber and an electric fuel pump.

Question 1: Do you have a fuel return line set up to the tank?
Question 2: Does the electric fuel pump get louder as the engine shuts off? (If so that would indicate vapor lock to me.)
Question 3: Are you idling when it shuts down, or will it shut off when you are cruising at 45 mph in gear?

I replaced the electric pump with an OEM fuel pump (later ones have a fuel return), and I teed in a fuel return line post pump using an auto parts store fuel filter as seen below. The return line is the one heading back.

Good luck. And keep troubleshooting before throwing parts at it.

 

[456z]

It starts up just fine after it sits. Usually on the first or second rev. It starts the same way every morning too. I pump the gas twice and it fires up immediately.

I haven't poured gas into the carb. I mentioned earlier I've pulled the fuel line right at the carb right at shut off and dumped it into a bottle and keyed on the truck and got fuel flow.

Great information as now we know that you have fuel in the carb bowl when it won't run.
so now I see it as 3 possibilities
1:the one I lean towards is a vacuum leak thus gas in the carb not getting sucked into the intake. Can easily be determined with a vacuum gauge. specifically I still suspect intake to head as you have headers but won' now without testing.

2:Something heat related is messing up you timing. Easily checked with a timing light.

3:lastly in my mind is you have described how hot the engine compartment is and makes me wander if it is possible that this might be affecting the fuel that is in the carb. don't know if this even can happen while it is running - just thinking.

 

[FJ4013]

Great information as now we know that you have fuel in the carb bowl when it won't run.
so now I see it as 3 possibilities
1:the one I lean towards is a vacuum leak thus gas in the carb not getting sucked into the intake. Can easily be determined with a vacuum gauge. specifically I still suspect intake to head as you have headers but won' now without testing.

2:Something heat related is messing up you timing. Easily checked with a timing light.

3:lastly in my mind is you have described how hot the engine compartment is and makes me wander if it is possible that this might be affecting the fuel that is in the carb. don't know if this even can happen while it is running - just thinking.

I have an import shop around the corner from me and while these guys don't specialize in FJ40s they have seen quite a few over the years. The owner thought it was fuel evaporating out of the Weber 38/38 I run. He said they have a small fuel bowl and heat from the manifold and header is making it evaporate.

He wanted me to wrap the header to abate heat.

I've also recently discovered this which I was unaware was even made. A carb heat shield:

Heat Shield for Carb

• FJ4013
• Sep 12, 2018

 

[SteveH]

I honestly know more local people who have had problems with Pertronix ignitions than those who have not. The failures I have seen were fatal - the vehicle dies while running and never restarts. You may have a heat-related occasional failure in the module.

I would consider getting a spare module for the distributor and swapping that in. If it doesn't solve the issue, then you have a trail spare.

 

[FJ4013]

I honestly know more local people who have had problems with Pertronix ignitions than those who have not. The failures I have seen were fatal - the vehicle dies while running and never restarts. You may have a heat-related occasional failure in the module.

I would consider getting a spare module for the distributor and swapping that in. If it doesn't solve the issue, then you have a trail spare.

I think another poster mentioned that as well. The engine shut off existed before the Pertronix install.

 

[hobbes]

@Weber Sarge might have idea. He’d know more about the carbs than most.

 

[65swb45]

Not mentioned so far: weakened ignition terminal contact in the ignition switch on the column.

 

[456z]

I have an import shop around the corner from me and while these guys don't specialize in FJ40s they have seen quite a few over the years. The owner thought it was fuel evaporating out of the Weber 38/38 I run. He said they have a small fuel bowl and heat from the manifold and header is making it evaporate.

He wanted me to wrap the header to abate heat.

I've also recently discovered this which I was unaware was even made. A carb heat shield:

fj4013. I think you are on the right track here as this would explain the relatively short thermal recovery time.
I run headers on my 79, stock carb with a carb heat shield. When I rebuilt my rig I added headers with the knowledge gleaned from these forums that it would add more heat in the engine compartment. I also added a o2 just downstream of the collector. What I learned from reading the o2 sensor as I drove was that I was running rich. As you described about the heat from the firewall being excessive I also found the same thing. But after much goofing around with timing and jets I got the mixture right and the heat was gone. In fact I had to wrap the headers at that point to keep the exhaust warm down to the o2. Hope you have long/skinny arms to wrap the the headers while they are on the rig. Also most people would tell you that wrapping the header unless they they are stainless will cause them to rust out quicker. Just saying if your assessment of excessive heat is the same as mine then your fuel is still burning in the header caused by either or both timing/rich jetting.

Please let us know what you learn.

 

[FJ40newmechanic]

There was also the report of sluggish starter performance after the shutdown. Evaporating fuel due to heat wouldn't explain that. The fact that he better insulated the exposed coil wire from the starter and the sluggish starter performance has since gone away, and the time it takes to cause a shutdown has increased in one of his latest tests, suggests to me that this is still an issue more on the electrical side or he has multiple issues going on. I have a hard time believing the Toyota Engineers would have missed a thermal issue causing evaporating fuel. You would think that would have been found really quick during the decades of field use.

 

[hobbes]

You’re probably correct in the electrical thing since there was a change. On the vapor lock issue, however, when one has an aftermarket carb, non-OEM fuel line routing, non-OEM fuel pump type, and modern fuel blends, Mr T’s Engineers are off the hook. My truck was living proof....

 

[FJ40newmechanic]

You’re probably correct in the electrical thing since there was a change. On the vapor lock issue, however, when one has an aftermarket carb, non-OEM fuel line routing, non-OEM fuel pump type, and modern fuel blends, Mr T’s Engineers are off the hook. My truck was living proof....

Great counter point. The saga continues.

 

[Steamer]

Just thinking of a possibility that I don't believe has been mentioned yet.
When it dies you said you still have spark and fuel.
Maybe it's too much fuel. Maybe the float valve isn't sealing good and it's flooding out. After 10 minutes or so, it evaporates and then it starts again. Just a thought.

 

[FJ4013]

Update and hopefully those who have offered many suggestions will see this.

Engine shut down today while at the shop of my friend who works on these rigs every day. Check spark and good there. Check fuel and no bueno. Bone dry. Maybe a drop came out. I turned it over again and we got minor fuel flow. This explains why the last time I checked for fuel I thought I was good. But it wasn't. He thinks the electric fuel pump I was running was only intermittently working and causing the fuel flow to be bad and ultimately vapor locking.

So we installed a mechanical fuel pump. I drove it for 30 minutes in hot Florida weather, idled at plenty of lights, drove on the freeway for 20 minutes at 65 so the engine had plenty of opportunity to stall out when I got stuck back in traffic and it did not stall once. I plan on taking it out tomorrow during the hottest part of the day and doing my best to see if it will stall. Hopefully this is the cure.

Thanks to everyone for putting up with my lack of knowledge on these rigs. I genuinely appreciate the help. I will update this in a couple of days to let everyone know if this fixed the problem.

If anyone has knowledge to share on why mechanical fuel pumps vs electric fuel pumps are better in these rigs then please share. I'm always wanting to learn more about these amazing trucks. How long should I expect a mechanical fuel pump to last assuming it is in good condition? The one we put on today was stripped off of another FJ40 that was in good running condition. With my electric fuel pump I always carried a spare around.

 

[FJ40newmechanic]

I bought a new OEM mechanical fuel pump for my 78 2F engine from City Racer LLC just this past week, so they are still available if you wanted to get a new one vs use an unknown remaining life used one. I haven't seen any rebuild kits with the diaphragm, only new units, so I don't know if you can rebuild them or not.

If you remove the electric fuel pump, post a picture, and list the model number / brand so we can check it out.