You just described exactly what it is doing. Set the cruise at about 45 MPH, engine running at 1700ish RPM. You can hear and feel engine power drop out for about a second, then comes back for about 3 seconds, and repeats over and over. Smoke at startup and accelerating has never been this bad either. Damn, one thing after another with this truck anymore. I'll get one ordered...
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What did you do with your GMT400 today...or yesterday....
- Thread starter deejaaa
- Start date
You just described exactly what it is doing. Set the cruise at about 45 MPH, engine running at 1700ish RPM. You can hear and feel engine power drop out for about a second, then comes back for about 3 seconds, and repeats over and over. Smoke at startup and accelerating has never been this bad either. Damn, one thing after another with this truck anymore. I'll get one ordered...
Husker6.5
135' diagonal 16:9HD, 25KW sound!
They used to say back in the day (like 2000-2002ish) that an IP was good for about 150K miles then tou should think about replacing it. Now, with both the ULSD adding to internal wear if a lubricant isn't used in the fuel and the fact there's no telling how many times that core has been rebuilt previously and/or what's been replaced in that "rebuild", probably closer to 100K or less for the life of an IP any more.
It is sitting at 116k right now. I have owned it for about 3 years, and have gotten the impression it has been a horse that was ridden hard and put away wet. It has had a lubricity additive in the tank since I have owned it, but no telling what was done before me. I don't know if the shop that replaced the heads moved it when pulling injector lines or if they pulled the pump with lines attached. Something hasn't been right since.
Husker6.5
135' diagonal 16:9HD, 25KW sound!
It's possible that they did disturb the IP in removing the injector lines when pulling the heads (though I don't know why, I've never had to move the pump for any reason when pulling my heads). You're right, no telling what the PO(s) did or didn't do for Preventative Maintenance prior to your getting the beasty. Your using a lubricity additive to the fuel wouldn't undo the wear/damage caused by his not using one, nor would it slow down any more wear from occurring if it had already started prior.
Big T
Well-Known Member
I thought the rule of thumb back in the day was 120K miles for the IP?
Will L.
Well-Known Member
Lube, incoming fuel pressure, and stopping all moisture are the 3 keys.
In the fleet of high daily mileage- like 100,000 miles in a year- we saw 250,000 all the time. Know that this was with real diesel, and low sulfur diesel which was a change from something like 3000 parts sulfur to 500 parts sulfur with lube additive. I can’t say since ULSD which is 15 parts per million.
We did run many trucks with the LSD fuel and NO added lube. They still all got over 150,000 miles on ip.
But I cannot stress enough the importance of fuel pressure. We learned that early and stuck to it...
In the fleet of high daily mileage- like 100,000 miles in a year- we saw 250,000 all the time. Know that this was with real diesel, and low sulfur diesel which was a change from something like 3000 parts sulfur to 500 parts sulfur with lube additive. I can’t say since ULSD which is 15 parts per million.
We did run many trucks with the LSD fuel and NO added lube. They still all got over 150,000 miles on ip.
But I cannot stress enough the importance of fuel pressure. We learned that early and stuck to it...
Will L.
Well-Known Member
Thats why i am doing an electric fuel pressure gauge with 2 sensors- one pre filter and one at ip. If will read ip all the time then momentary switch to read prefilter. Should be pretty easy to determine when a filter is due as opposed to “X” miles or hours. You dont know how much debris came up from the fuel station. Maybe normally 10,000 miles is good then next time 4,000 got same amount of dirt.
Husker6.5
135' diagonal 16:9HD, 25KW sound!
The IP on my 98 Burb was acting up (light surging causing the TCC lock/unlock symptoms) when I bought it at 200K, service history of the previous owners unknown. I put a new set of injectors on since I assumed at 200K it was due for a new set whether they were original of had been replaced at 100K, and the surging diminished and was a lot less noticeable for the next 20-25K miles, then the surging came back with a vengeance (was starting to becoming noticeable again on the trip back from NYC and fuel mileage took a 2-3 mpg drop) and took out the transmission about 3,000 miles and three months later. That IP is still on my transmission-less Burb. I've never bothered to check if it's the original or a reman IP. Never had an IP issue on my 94 when both the heads cracked at 245K miles. I bought it with 190K on it. I know there's a reman pump on it that was the one on it when I bought it (not sure how many pumps had been put on it under warranty by the original owner under warranty due to the PMD failing being confused with the IP going out by service techs), but like the Burb, I always added FuelServices Diesel Treat every tank in warm weather and their anti-gel in cold weather.
No clue as to the previous maintenance (or lack thereof) to the Burb. It started out life as a rental unit out of the Orlando area, had three other owners in Florida before being bought at auction by the dealer I bought it from out of Mooresville, NC.
So, as @Will L. was saying, consistent preventative maintenance plays a big part in longevity of the IP, but with used vehicles that's a crap shoot at best.
The easiest test to see if it's your IP taking a dump is the 2000 rpm steady-state test. Basically, with a warmed up to running temp engine, tranny in Park (or Neutral if a manual) hold the accelerator pedal steady so that the engine maintains a constant 2000 rpm. If the engine hunts up and down rpm with the pedal steady (surges), good indication your IP is wearing out internally.
No clue as to the previous maintenance (or lack thereof) to the Burb. It started out life as a rental unit out of the Orlando area, had three other owners in Florida before being bought at auction by the dealer I bought it from out of Mooresville, NC.
So, as @Will L. was saying, consistent preventative maintenance plays a big part in longevity of the IP, but with used vehicles that's a crap shoot at best.
The easiest test to see if it's your IP taking a dump is the 2000 rpm steady-state test. Basically, with a warmed up to running temp engine, tranny in Park (or Neutral if a manual) hold the accelerator pedal steady so that the engine maintains a constant 2000 rpm. If the engine hunts up and down rpm with the pedal steady (surges), good indication your IP is wearing out internally.
Will L.
Well-Known Member
Care to show which you would recommend? Being as both locations better be under pressure not vacuum, I don’t understand why get something not available at any Autoparts store for low cost and future availability.
Husker6.5
135' diagonal 16:9HD, 25KW sound!
I disagree with that solution for several reasons: First, a pre-filter pressure reading will give you a good indication of the lift pump's health.
Second, without a baseline reference of pre and post filter pressures, knowing the differential between the two is meaningless. Example: Differential is 5 psi. Does this mean the pre-filter pressure is 18 psi (healthy lift pump) and IP inlet pressure 13 psi (newer, good filter and healthy IP inlet pressure), or does the 5 psi differential mean pre-filter pressure is 6 psi (dying/dead lift pump) and IP inlet pressure is 1 psi (filter is ok, but the IP is going to be killed by the lack of inlet pressure).
Third. Simplicity/Cost. With two pressure senders, one gauge and a switch to select which input to the gauge, a simple system that has parts easily and cheaply available at any local auto parts store and can be easily installed by the average Do-it-yourself owner.
denata
Well-Known Member
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Aliexpress link
The state of the filter is determined by the pressure drop on it.
The state of the filter is determined by the pressure drop on it.
Will L.
Well-Known Member
The gauges that showed up in your link- they are simply measuring pressure/ vacuum in pascals rather than psi. Also they would require running the fuel lines into the cab. Then you also have an industrial gauge to somehow mount to your dash or a custom gauge mount to be made. Also you need to find the gauge that is rated for diesel fuel, ethonal and methanol based on where you are filling up.
While pascals are more accurate incriminating,1 psi = 6894.75728 Pascal, I dont think reading that accurate of measurement is going to be needed or would be any easier.
Consider:
I will reference desired ds4 numbers. Using a psi gauge pre and post filter. Pre filter is at 15psi and post filter is at 14psi. There is a pressure differential of 1 psi. Filter is restricting but at an Acceptable limit. Now as the filter plugs you will still see 15psi pre filter, and post filter is at 10 psi. So a differential of 5psi. What does the driver know? He is still at s safe level of pressure that he is not causing harm to the injection pump, so he can continue to drive. If he notices there is a loss in power once post filter gets to 8psi, although he still is doing no damage to the ip, he can change the filter and learn where the felt power drop is affected. Now for the future he learns to replace the fuel filter at 9 psi.
With the gauges you posted- he needs 2 isolators to stop the fuel entering the cab, because the pulsing Of any fuel pump will vary 0.5 psi, or approximately 3,400 pascals. You should NOT use a liquid filled gauge because when the lift pump begins failing you want to see the rapid fluctuations as part of diagnostics. Yes the gauge shows the pressure differential indicating a plugged filter - if you know the appropriate pressure differential already. You could learn what that is the same way- but you still need to know how what the fuel pressure is at the injection pump, not just the filter pressure differential. So now you are buying and mounting another gauge.
When daily driving the vehicle, a person glances at speed, fuel tank level, oil pressure, coolant temperature, battery voltage. To also at a glance just see you have acceptable fuel pressure to know you aren’t damaging the injection pump is akin to seeing oil pressure to know the engine is ok. A person would only care to know filter condition when either something is acting wrong and in pursing diagnostics, or a couple times a year to see if the fuel filter ready for replacement on the next oil change. I really see no reason to add a dedicated gauge, two fuel lines, two isolators, a custom gauge mount for this purpose. Especially when if a person adds a fuel pressure gauge to know the ip is safe, a simple second sensor, and a $1 button is all thats needed And the fuel pressure gauges can be mounted in place of any normal gauge in a pillar mount or like most Hummer guys now do- in place of the dial clock thwt most are broken anyways.
Just my 2c, feel free to do the set up you show. Please post pics & links when you do it so others that like your system can copy it.
While pascals are more accurate incriminating,1 psi = 6894.75728 Pascal, I dont think reading that accurate of measurement is going to be needed or would be any easier.
Consider:
I will reference desired ds4 numbers. Using a psi gauge pre and post filter. Pre filter is at 15psi and post filter is at 14psi. There is a pressure differential of 1 psi. Filter is restricting but at an Acceptable limit. Now as the filter plugs you will still see 15psi pre filter, and post filter is at 10 psi. So a differential of 5psi. What does the driver know? He is still at s safe level of pressure that he is not causing harm to the injection pump, so he can continue to drive. If he notices there is a loss in power once post filter gets to 8psi, although he still is doing no damage to the ip, he can change the filter and learn where the felt power drop is affected. Now for the future he learns to replace the fuel filter at 9 psi.
With the gauges you posted- he needs 2 isolators to stop the fuel entering the cab, because the pulsing Of any fuel pump will vary 0.5 psi, or approximately 3,400 pascals. You should NOT use a liquid filled gauge because when the lift pump begins failing you want to see the rapid fluctuations as part of diagnostics. Yes the gauge shows the pressure differential indicating a plugged filter - if you know the appropriate pressure differential already. You could learn what that is the same way- but you still need to know how what the fuel pressure is at the injection pump, not just the filter pressure differential. So now you are buying and mounting another gauge.
When daily driving the vehicle, a person glances at speed, fuel tank level, oil pressure, coolant temperature, battery voltage. To also at a glance just see you have acceptable fuel pressure to know you aren’t damaging the injection pump is akin to seeing oil pressure to know the engine is ok. A person would only care to know filter condition when either something is acting wrong and in pursing diagnostics, or a couple times a year to see if the fuel filter ready for replacement on the next oil change. I really see no reason to add a dedicated gauge, two fuel lines, two isolators, a custom gauge mount for this purpose. Especially when if a person adds a fuel pressure gauge to know the ip is safe, a simple second sensor, and a $1 button is all thats needed And the fuel pressure gauges can be mounted in place of any normal gauge in a pillar mount or like most Hummer guys now do- in place of the dial clock thwt most are broken anyways.
Just my 2c, feel free to do the set up you show. Please post pics & links when you do it so others that like your system can copy it.
Husker6.5
135' diagonal 16:9HD, 25KW sound!
MrMarty51
Well-Known Member
My truck, I think, is needing a radiator. I have not yet managed to get that ordered, However though, I did get that CC paid off for the month, and, instead of a radiator, I ordered a new coolant pump from Leroy diesel. I did replace the coolant pump maybe six to eight thousand miles ago, with a unit from NAPA, However and for reasons unknown, it seems that I just dont trust that pump. It might be good enough, but, to Me, good enough is not good enough. i want the best that is available.
After getting the pump paid for, then will come the radiator and, replace them both while the coolant is drained.
And, while in the process, i am going to pull T-Stats and drop the temp rating on those too, probably 185 degree units.
I just do not want to ever have to go through another one of those hours long, nail biting experiences like I did last summer.
The other morning after I fired up the truck. I pulled the oil fill cap and could not detect one bit of blow by. I am wondering though, does the CDR valve need to be disabled to perform this test ?
I did block off the motion of the fan and still no blowby was detected.
After getting the pump paid for, then will come the radiator and, replace them both while the coolant is drained.
And, while in the process, i am going to pull T-Stats and drop the temp rating on those too, probably 185 degree units.
I just do not want to ever have to go through another one of those hours long, nail biting experiences like I did last summer.
The other morning after I fired up the truck. I pulled the oil fill cap and could not detect one bit of blow by. I am wondering though, does the CDR valve need to be disabled to perform this test ?
I did block off the motion of the fan and still no blowby was detected.
Come home from work tonight to a massive puddle of fuel under the front of the truck... looks like it is coming from the second injector back on the driver side. The truck hasn't moved in 2 days, so I can't think of why it would randomly start dripping fuel all of the sudden. I started it to move it off the driveway and I can see bubbles on one of the return hoses. I think I'm going to be going through the entire fuel system when I do the IP.
Will L.
Well-Known Member
Good plan
Husker6.5
135' diagonal 16:9HD, 25KW sound!
Sounds like it's time for some new return hoses for the injectors.
I bet the shop that did the head change reused the old hoses...