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Cranks, starts, dies.

wankel1308

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Hey guys, I've got a cranks, starts, dies issue. I've eliminated all the easy stuff, MAF, IAC, crank sensor, and my fuel pump delivers tons of volume. What are the chances that the fuel pump can deliver volume but not pressure? I'm also inclined to suspect the Cam position sensor, and the primary fuel pump circuit.

Yes, obviously I should get a fuel pressure tester... But I figured I'd ask the experts.
 


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Nadams01

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1991 explorer eddie bauer
Hey guys, I've got a cranks, starts, dies issue. I've eliminated all the easy stuff, MAF, IAC, crank sensor, and my fuel pump delivers tons of volume. What are the chances that the fuel pump can deliver volume but not pressure? I'm also inclined to suspect the Cam position sensor, and the primary fuel pump circuit.

Yes, obviously I should get a fuel pressure tester... But I figured I'd ask the experts.
Volume? Factory spec for fuel pressure is 40 to 45 psi. Hard to gauge volume just on how much fuel comes out from where ever your measuring. Rent a pressure test kit from a parts store and test at the port located under the intake manifold next to the injectors. Check your EEC fuse that supplies power to the fuel pump relay and eec relay. 1st gens do not have a cam shaft position sensor, just a crank. If your getting fuel more than likely the pcm doesn't want to continue to send spark for a givin reason. Did you replace the crank shaft position sensor? As proper testing requires an oscilloscope to make sure the pickup from the magnet on the crank is flat and even.
 




wankel1308

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Volume? Factory spec for fuel pressure is 40 to 45 psi. Hard to gauge volume just on how much fuel comes out from where ever your measuring. Rent a pressure test kit from a parts store and test at the port located under the intake manifold next to the injectors. Check your EEC fuse that supplies power to the fuel pump relay and eec relay. 1st gens do not have a cam shaft position sensor, just a crank. If your getting fuel more than likely the pcm doesn't want to continue to send spark for a givin reason. Did you replace the crank shaft position sensor? As proper testing requires an oscilloscope to make sure the pickup from the magnet on the crank is flat and even.
Appreciate the reply! I'm getting the pressure tester today. The crank sensor is in fact brand new and was replaced the first time I had this issue. It mysteriously fixed itself overnight the last time....

The 1993 and up Ford 4.0 OHV does in fact have a cam sensor. Mine is a 94. It is located on the back of the block where the distributor should be. The sensor monitors #1 cylinder to tell the injectors when to fire. It has 3 wires, red (12v), black and white (ground), and dark blue/orange (signal). All the wires test good all the way back to the ECM. The signal can be monitored via DVOM, I just need a buddy to crank the motor while I watch the gauge and I'll have that verified.

What would cause the ECM to cut spark? Lack of signal from the crank sensor? I pulled a plug and it sparked the entire time we turned the engine over and the tach rises while cranking. That to me indicates that I have plenty of spark.

Edit:
Have purchased, finally, a can of carb cleaner. The truck ran when squirted. I will update for google posterity if/when a new fuel pump fixes it.
 




wankel1308

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Well... I put the brand new fuel pump in. It still has exactly the same problem. Plenty of fuel getting to the rail but it's not coming out of the injectors. I can manually ground the pump through the ecm diagnostic port and it still won't stay running. This indicates that the run part of the start/run circuit is operational? Do all the injectors fire as part of initial key on the same way the fuel pump runs for 2 seconds? What would tell the injectors to stop firing?

Anybody have any thoughts or advice???
 




Nadams01

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1991 explorer eddie bauer
Appreciate the reply! I'm getting the pressure tester today. The crank sensor is in fact brand new and was replaced the first time I had this issue. It mysteriously fixed itself overnight the last time....

The 1993 and up Ford 4.0 OHV does in fact have a cam sensor. Mine is a 94. It is located on the back of the block where the distributor should be. The sensor monitors #1 cylinder to tell the injectors when to fire. It has 3 wires, red (12v), black and white (ground), and dark blue/orange (signal). All the wires test good all the way back to the ECM. The signal can be monitored via DVOM, I just need a buddy to crank the motor while I watch the gauge and I'll have that verified.

What would cause the ECM to cut spark? Lack of signal from the crank sensor? I pulled a plug and it sparked the entire time we turned the engine over and the tach rises while cranking. That to me indicates that I have plenty of spark.

Edit:
Have purchased, finally, a can of carb cleaner. The truck ran when squirted. I will update for google posterity if/when a new fuel pump fixes it.
My apologies I have a 91 with only a crank sensor. If they injectors are not squirting fuel I would hook up a multimeter or noide light to see if they are receiving signal to fire.
 




wankel1308

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Well, I put the fuel pump in and that didn't fix it. So I got frustrated and let it sit a few days and when my friend arrived to give me a hand, it started immediately. I drove it around the block, put new rear shocks on (that was my project before it shut down), took it on a few errands and it ran great. It stumbled once. I don't believe that it's fixed. But I'm now suspecting maybe it's an ecm issue. Who knows.... I'll update next time it dies.
 




OneofMany

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Sounds like a textbook IAC problem but if the fuel pressure is too low, it will do the same thing. If it is the IAC or the control circuit, pressing the throttle while cranking should stop it dieing when you let off the starter. You may need to check injectors and fuel filter to be sure the engine is actually getting enough fuel. Check fuel pressure while running and pulling a hill.
 




wankel1308

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So it ran great Thursday and wouldn't start again on Friday morning.... It cranks, catches and dies immediately. I have spark and fuel. The fuel pump is new. I can manually run the fuel pump using the diagnostic port. The truck still will not run. Something is not letting the injectors fire.

I have codes 335 and 556. 335 is EGR valve high voltage. 556 is fuel pump primary circuit failure. Now, I understand that the fuel pump circuit could be the issue, but does a high voltage fuel pump code shut down the engine? Most cases of 556 are symptoms like runs rough, stumbles, low power, etc but the engine still runs. Can the PCM shut down the engine for that code? I would think that with the pump circuit grounded and the pump running I could make it run(shrug) The only thing that makes sense is that the injectors aren't firing. That said, I have no injector related codes and no cam signal related codes.
 




OneofMany

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Find a diagnostic tree for the 556 code
 








Nadams01

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Got a source??
Oh no, check the inertia switch. Passenger side front floor board under carpet. Sometimes there iffy so fully press down on it. I should have said that earlier
 




92exp4x4

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The PCM controls the ground to the fuel pump relay. Could you have an issue there? Provide a ground to the control side of the relay or jumper it out and see if the truck runs. I know you mentioned something about grounding the diag port to run the pump. I would try jumping the relay as it's what is supposed to run the pump. Maybe it will make a difference.
 




wankel1308

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Turns out it's a bad PCM. No injector pulse.
 




92exp4x4

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That will do it. I've been wondering with these vehicles hitting 30 years old, just how many computer failures we will start to see.

I got hold of an '84 Benz with the 5.0L M117 gas engine about 4 years ago. It has a very primitive Lambda correction system that controls fuel trim on its mechanical fuel injection system. The module literally is 6 pins (I think)? When they start running crappy, the fix is to melt the solder for the pins on the card and let it re harden. This removes impurities that have formed in the last 35 years in the solder and created resistance in the circuit that caused the issue. Or replace the unit with a reman, which is what I did.

This is a very simple computer, the explorer is so much more complex. At the time I was thinking that this same thing could happen with the newer machines. I think we'll start to see a lot of issues like this over the next couple years.
 




wankel1308

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That will do it. I've been wondering with these vehicles hitting 30 years old, just how many computer failures we will start to see.

I got hold of an '84 Benz with the 5.0L M117 gas engine about 4 years ago. It has a very primitive Lambda correction system that controls fuel trim on its mechanical fuel injection system. The module literally is 6 pins (I think)? When they start running crappy, the fix is to melt the solder for the pins on the card and let it re harden. This removes impurities that have formed in the last 35 years in the solder and created resistance in the circuit that caused the issue. Or replace the unit with a reman, which is what I did.

This is a very simple computer, the explorer is so much more complex. At the time I was thinking that this same thing could happen with the newer machines. I think we'll start to see a lot of issues like this over the next couple years.
Appreciate your response. I've been wondering the same thing lately... For years the advice has been, "the ECM is NOT bad." I think those days are over...

I will probably retain the old PCM and resolder connections, likely replace a few caps and keep it around as a backup.

I have also been considering going to a standalone ECU, just to future proof these old dinosaurs. Plus, I'd really love to be able to read codes over Bluetooth.... But that's a pretty big expense for most of us to stomach on a $2500 truck...
 




92exp4x4

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Appreciate your response. I've been wondering the same thing lately... For years the advice has been, "the ECM is NOT bad." I think those days are over...

I will probably retain the old PCM and resolder connections, likely replace a few caps and keep it around as a backup.

I have also been considering going to a standalone ECU, just to future proof these old dinosaurs. Plus, I'd really love to be able to read codes over Bluetooth.... But that's a pretty big expense for most of us to stomach on a $2500 truck..
I've got a couple spares myself. I've parted trucks out over the years and have a bunch of spare parts from them. There will be companies that recondition this stuff, but as time goes on eventually those parts will dry up. And you're right, most of the time the cost of repair or refurbishing out weighs the value of the vehicle. It's nothing to have almost double the value of a given car in it's restoration.

I look for the old car hobby to change quite a bit in the coming years. As EVs begin to become more mainstream, I look for regulations to tighten up on older cars, possibly as early as in the next 10 years. London England already has put heavy fees on classic cars on top of the normal registration costs. Old car EV conversions are already a thing. I'm a purist, so I'm not quite so open to that. I have a lot of effort in some of these machines to make them as close to original as possible (not the Explorers yet), while still being able to use them. But modification in the name of preservation may be ours and our kid's only option eventually.
 




RADIOACTIVE_TOOL_SHED___

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That will do it. I've been wondering with these vehicles hitting 30 years old, just how many computer failures we will start to see.

I got hold of an '84 Benz with the 5.0L M117 gas engine about 4 years ago. It has a very primitive Lambda correction system that controls fuel trim on its mechanical fuel injection system. The module literally is 6 pins (I think)? When they start running crappy, the fix is to melt the solder for the pins on the card and let it re harden. This removes impurities that have formed in the last 35 years in the solder and created resistance in the circuit that caused the issue. Or replace the unit with a reman, which is what I did.

This is a very simple computer, the explorer is so much more complex. At the time I was thinking that this same thing could happen with the newer machines. I think we'll start to see a lot of issues like this over the next couple years.
My 1993 explorer sometimes has a hard time starting in colder weather I read somewhere on here that's what fixed there's if I run into the problem again I'll put a new ecu in it
 




wankel1308

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I've got a couple spares myself. I've parted trucks out over the years and have a bunch of spare parts from them. There will be companies that recondition this stuff, but as time goes on eventually those parts will dry up. And you're right, most of the time the cost of repair or refurbishing out weighs the value of the vehicle. It's nothing to have almost double the value of a given car in it's restoration.

I look for the old car hobby to change quite a bit in the coming years. As EVs begin to become more mainstream, I look for regulations to tighten up on older cars, possibly as early as in the next 10 years. London England already has put heavy fees on classic cars on top of the normal registration costs. Old car EV conversions are already a thing. I'm a purist, so I'm not quite so open to that. I have a lot of effort in some of these machines to make them as close to original as possible (not the Explorers yet), while still being able to use them. But modification in the name of preservation may be ours and our kid's only option eventually.
Weren't the explorers in Jurassic Park electric? I don't necessarily hate the idea, give me a 300 mile range battery pack the size of the spare tire and I'm in. Plus, you know I'd rather see classics whirring around on electricity than rotting away in people's backyards.
 




RADIOACTIVE_TOOL_SHED___

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Weren't the explorers in Jurassic Park electric? I don't necessarily hate the idea, give me a 300 mile range battery pack the size of the spare tire and I'm in. Plus, you know I'd rather see classics whirring around on electricity than rotting away in people's backyards.
If there was a ban or some kind of tax on internal combustion engine vehicles the first and 2nd gen explorers would probably be the first kinda vehicles to be banned in most of them would be scrapped because of their low cost unfortunately, I hope they never try to ban these things cash for clunkers already destroyed enough of them
 


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92exp4x4

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In the story they are electric powered. Ive got a JP project that I've been working on for a long time. It's been in storage for quite a few years now just waiting patiently. I've got a build thread on this forum actually. I've considered doing an EV swap and had some electric forklift parts at one time to do it. However the system was not going to be efficient enough to be useful, and may have only had a top speed of around 30 MPH. The truck probably would have weighed close to 6K with all the golf cart batteries it would have needed!

Now the technology is a lot different. I'll use forklift parts because I can get them fairly inexpensively. The biggest difference is AC drive. It's way more efficient and there is so much more available torque at a lower current draw. There probably won't ever be a spare tired sized battery pack for a vehicle this size, but never say never!!

@RADIOACTIVE_TOOL_SHED___ an all out ban on ICE vehicles in the US would be a hard sell. It would take a long time for things to got to that point. But I could see legislation forcing them off the road due to cost of registration and tax penalties, over time. Things change slowly and if you don't pay attention, you might get surprised one day.

I do embrace electrification, however it's wrong to penalize those that decide to keep the old stuff going. Especially when in the grand scheme, they don't amount to a drop in the bucket of emitters. Industry including agriculture, has more effect on CO2 emissions than all the vehicles on the road do. Attacking one tiny segment of the auto hobby is pointless. There are a lot of things changing right now. It's a rather exciting time to be living. I imagine the next ten years being almost as significant for auto technology as the days before 1930.
 




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