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TPS ? Fuel Pressure ? What You think ?

MrMarty51 said:
Mine has the split second key on cycle.
I have always wondered if that pig would ever give me grief.
Guess I better figure out how to reset it just in case it is the problem.
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if it only stays on for a split second and doesn't come back on there shouldn't be an issue with it. the light staying on would mean something has tripped it. is the truck back up and running after the new switch is installed?
 
dbrannon79 said:
if it only stays on for a split second and doesn't come back on there shouldn't be an issue with it. the light staying on would mean something has tripped it. is the truck back up and running after the new switch is installed?
Click to expand...
Switch is on the way. Probably be a couple of weeks before I can do any more to it.
Unless the son gets that Continental X out of the garage, then maybe I can get the truck into the shed and work on it after I get off work.
I did get the tuned ECM ordered through QS Tuning but that will not get added on until I am sure that the stalling issue is cured.
 
It has been a process of elimination.
Seems everything breaks at the same time.
Got that Continental removed from the shack.
Planning on using the MG for the daily driver and it too takes the notion for the enjun to stall and die.
Fuel pump was its problem. Installed a new Edelbrock unit rated at less than 4 PSI. Got that installed after several baths in gasoline, no way to stop that flow from the tank that was near full. Got it ready to roll, fired up the engine, out of the garage, around the corner and it dies. WTF. Roxanne and Vicki and myself we push it back into the garage.
Disconnect that pump and 0 suction and 0 pressure.
Back to the parts store, got an exchange, more gasoline baths and it now runs as it should. 65 MPH and the O2 gauge was reading 13.6. Perfect, I think. 🤷
Back to the truck, went to fire it up and barely got a grunt out of the batteries.
I forgot about the glove box lamp. Charged the batteries for several hours and it fires right up.
Into the garage, warm it up some then flip on the PTO option switches. 1600 RPMs.
First ten minutes the fuel pressure gauge was steady at 6 PSI.
When I first installed this pump/relay system pressure was at 9’under a load.
Pretty soon the gauge began to fluctuate, between five and six. A little more time and the gauge began to swing even more radically and falling off.
IMG_0341.jpeg
And then dropping lower.
IMG_0340.jpeg
And so I am beginning to think that this stalling could be related to a lift pump going out.
I do have the Facet pump that was installed on the truck when I purchased it.
Thinking I’ll install that back onto the truck and see how that works.
It is a lower PSI pump but the truck run okay until the temps went to about 20 below zero F. Then the pressure went to 0.
Warmer temps it showed pressure, just lower than what the IP likes.
 
Marty, those Edelbroken pumps are known to fail! there are a couple of other things to look at. is the FP mounted in any areas near heat, also not having fuel flowing constantly through the FP will kill them. they need some flow to keep from dead-heading and heating up. Vapor locking in the fuel lines can also kill the FP's. you might look at running a higher PSI pump and add an old skool regulator with return to the tank just to prevent the FP from vapor locking or dead heading to the carb.
 
dbrannon79 said:
Marty, those Edelbroken pumps are known to fail! there are a couple of other things to look at. is the FP mounted in any areas near heat, also not having fuel flowing constantly through the FP will kill them. they need some flow to keep from dead-heading and heating up. Vapor locking in the fuel lines can also kill the FP's. you might look at running a higher PSI pump and add an old skool regulator with return to the tank just to prevent the FP from vapor locking or dead heading to the carb.
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Built a bracket and mounted the pump bottom of the tank level.
No heat from exhaust etc in the vicinity.
I do have three SU fuel pumps, original to the MG vehicles.
The pump original to this car has a burned up condenser, they are still available, The pump from another MG that I scrapped out is in nice condition. Dismantled it and sanded the points to bright and shiny. Reassembled, adjusted the diaphragm, hooked it to a battery and it ticks right along. Holds pressure, a tick at a time to maintain pressure or series of ticks when free flowing.
I misplaced the rubber mounting grommet so going to order one of those and a set of points and a condenser. Then I’ll have a spare original pump.
 
So far edelbroke (😹) fuel pump is functioning okay. MG made two round trips to work and back home again. 😂
Thinking back on the run in the garage watching the fuel pressure.
I did have the fuel cap loose while running the engine.
I forgot, it was extremely hot inside the cab of the truck.
I turned on the AC of the truck to kind of cool it down in there, and, now, I’m thinking that the FP began to wildly fluctuate when the AC was engaged. Truck cooled down so I turned off the AC.
I’ll be conducting another run time test but this time, with the AC running and then not running and see if the FP does fluctuate with and without the AC running.
Might be a grounding issue or a going bad AC clutch sucking the life out of the electrical system causing the gauge and FP to change like that.
Maybe tonight after working I’ll have an updated report.
 
Here is on the 2000 K3500.
When the switch lights up is when the AC is turned on, when the pressure goes way low is when the HVAC blower gets engaged.
Turn it all off and the FP goes back up to five or above.
Maybe I need to find a different electrical power source for the fuel pump.
It does have the Leroy Diesel relay/carter fuel pump system installed.

 
trace the main power source to the relay and see where it's connected. it should be going with a fuse direct to the battery. they'll be two power sources to the relay one is the main which carries the juice to the pump, the other is simply to energize the relay which comes from the OPS. the main will be hot at all times even with the key off. I'm betting your getting the main power from the fuse box that also supplies power into the cab for accessories.

one other thought is what is your volt meter doing in the dash when this is happening? you may also have a bad connection getting power into the cab on this same power source. this can be contributing to the shut down not starting condition.
 
dbrannon79 said:
trace the main power source to the relay and see where it's connected. it should be going with a fuse direct to the battery. they'll be two power sources to the relay one is the main which carries the juice to the pump, the other is simply to energize the relay which comes from the OPS. the main will be hot at all times even with the key off. I'm betting your getting the main power from the fuse box that also supplies power into the cab for accessories.

one other thought is what is your volt meter doing in the dash when this is happening? you may also have a bad connection getting power into the cab on this same power source. this can be contributing to the shut down not starting condition.
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Power for the pump relay is direct off one of the battery terminal lugs on the rearward side of the underhood fuse/relay box.
I’ll getta pic of that tomorrow.
 
Carter lift pump is making pretty loud noises.
Engine not running, key on to activate gauge, everything turned off except the LP bypass air bleed switch.
IMG_0369.jpeg

I’m not certain that the LP is the problem but when it was initially installed it was running right at, or about ten or more pounds.
Also since problem started, changed the pre LP inline filter.
PO had explained that He had removed the tank and pulled the screen sock and installed the inline 3/8ths pre filter.
 
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Today, after work. I’ll hook up the exhaust hose and run the engine once again, checking and watching the in dash volt meter.
Maybe hook the multimeter to the battery connection at the underhood fuse box too.
 
MrMarty51 said:
Carter lift pump is making pretty loud noises.
Engine not running, key on to activate gauge, everything turned off except the LP bypass air bleed switch.
View attachment 89472

I’m not certain that the LP is the problem but when it was initially installed it was running right at, or about ten or more pounds.
Also since problem started, changed the pre LP inline filter.
PO had explained that He had removed the tank and pulled the screen sock and installed the inline 3/8ths pre filter.
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Looks like it's a lift pump issue.
It may be requiring a lot more juice if it's bad.

I would try with the pre filter bypassed or with a 50 micron inline or a large filter with high volume in it's place.

Even if the FFM filter is plugged, the pressure would probably come up eventually.

Did you run about 1/2 gallon out of the drain T?
 
jrsavoie said:
Looks like it's a lift pump issue.
It may be requiring a lot more juice if it's bad.

I would try with the pre filter bypassed or with a 50 micron inline or a large filter with high volume in it's place.

Even if the FFM filter is plugged, the pressure would probably come up eventually.

Did you run about 1/2 gallon out of the drain T?
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No, i sure did not, run fuel out the T connection.
I will give that a try.
Never occured to me it might be an O2 overload. 😹
 
MrMarty51 said:
Brightest red wire is the LP relay system main feed wire. It must be a ten or at least a twelve gauge.
View attachment 89470

Large red wire is the feed from the battery posts.

View attachment 89471
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Marty, am I looking at the two posts that reside on the back side of the under hood fuse box? those two posts provide power from the two MAXI fuses in the box. they are both on separate fuses that should be labeled AUX1 and 2.

this might be your issue. this fuse box is supplied power from a 10gwg wire that comes from the captains side battery which is barely enough to run the existing items it supplies. adding a wire from the battery to one of these posts and using a 60a fuse might help some but the contact pins within the under side of this box are also thin and small. It looks like there is too much connected to both of the aux studs.

on my 95 truck I have used a amp clamp on the wire that supplies power to this entire box and when the engine is running with the AC there was a 40+ amp draw on this wire! adding the fuel pump would increase this to around 50amps. there should be a fusable link within the wire at the battery that goes to this box. on mine it was getting quite warm with everything running. I did run an extra wire from the back of my alternator to one of the aux posts and installed a 50 amp fuse there which did help but not much.

What you need is a bus bar like the older trucks used that was mounted up on the firewall. use a 6 or 8awg wire and a re-settable breaker like is used for running a hot wire to a car stereo amp to this bus bar. Then move all those extra wires from those two studs over to the new bus bar.
 
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I need to somehow come up with a keyed power source.
One thats not live until the ignition is switched to run.
One or two big relays, 50 amp would be good then run those from a dedicated battery terminal with a 50 amp fuse right off the battery post.
John Deere has a battery terminal bolt that has a stud hanging from the head end. Those are mighty slick for running auxiliary power sources.
 
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