Fuel pressure gauge

[SShafranko]

Does anyone know if a fuel pressure gauge will help me to determine injector failure by reading a pressure drop so that the truck could be turned off before further damage occurs? Thnx.

 

[JVolpe]

I doubt it. There would have to be a signficant increase in rail pressure to show at the lift pump readings. I don't believe a bad injector would cause issue that would be seen at the fuel pressure level or at least not enough for that diagnosis. But that is just my opion. I have had injectors stick wide open and that did not show any significant fuel pressure drop.

 

[steved]

The only way it would is if the body cracked, you could possibly see a drop in rail pressure.

Additionally, if the rate of fuel return to the tank is high, this would translate into lower rail pressure.

With that said, when I lost the injector last night, there was no change in rail pressure...

steved

 

[RMalone]

I agree, from what I know the only way to truly isolate a bad injector is to do just that, isolate each injector. I haven't done it but I hear its a bit of a pain.

 

[SShafranko]

I agree, from what I know the only way to truly isolate a bad injector is to do just that, isolate each injector. I haven't done it but I hear its a bit of a pain.

Ty. Are you saying install a gauge for each injector?... ... . Sounds like a plan

 

[steved]

Ty. Are you saying install a gauge for each injector?... ... . Sounds like a plan

And what will you use for a guage? What is your sending unit?? You realize you're talking 20k psi right??



Not that it couldn't be done, but why?



steved

 

[SShafranko]

And what will you use for a guage? What is your sending unit?? You realize you're talking 20k psi right??



Not that it couldn't be done, but why?



steved

Sorry. Not really too familiar with diesels. Trying to learn thats why i'm here. As for why I would love to know that my injector just krapped out right before it shoots gallons of fuel past the piston.

 

[steved]

These 3rd gen trucks run around 20k psi at the rail/injector... I know that sending unit for rail pressure (that runs the rail pressure) is pricey, even through cummins.



I doubt you'd see anything at a single injector... the rail would equalize and you'd see the same, albeit lower, pressure at all 6 injectors.



I'm a little disappointed that an injector can fail, and not trip a MIL or set a code to warn the driver there is a problem...



steved

 

[SShafranko]

These 3rd gen trucks run around 20k psi at the rail/injector... I know that sending unit for rail pressure (that runs the rail pressure) is pricey, even through cummins.



I doubt you'd see anything at a single injector... the rail would equalize and you'd see the same, albeit lower, pressure at all 6 injectors.



I'm a little disappointed that an injector can fail, and not trip a MIL or set a code to warn the driver there is a problem...



steved

Exactly what i'm trying to say. There is no warning. Sorry guess i just worded it wrong. Definetly good idea to have a fuel pressure gauge. (im assuming)

 

[steved]

I have a rail pressure guage (based on the OE sensor) and saw not change when I lost my injector last night... it might show some failures (there are several types of "failures"), but not all...

steved

 

[SShafranko]

I have a rail pressure guage (based on the OE sensor) and saw not change when I lost my injector last night... it might show some failures (there are several types of "failures"), but not all...



steved

Gotcha. I'm going to install it because i plan on installing 50hp injectors, releasing level 6 on the edge and a turbo. I'm guessing that i should probably monitor my rail pressure and will definitely need some fuel mods. I'm doing the injectors first; do you think i will need any fuel mods with the inj. upgrade alone?

 

[steved]

I'm doing the injectors first; do you think i will need any fuel mods with the inj. upgrade alone?

Sorry, I'm the wrong person to ask... that's something I don't know...



steved

 

[betterthanstock]

The only reliable way to know if an injector is going bad, other than a change in sound, is an EGT guage for every cylinder. Three regular guages, one for every 2 cylinders, would be great.

even a dual gage like this would be good, one for the front 4, the other for the 2 rear cylinders.

MICRO-1000 DUAL EGT GAUGES from Aircraft Spruce Well, this one only starts at 1000deg, so it's kinda useless if one cylinder goes low on temperature.



I also like this one:

AEROSPACE LOGIC CHT/EGT INDICATORS from Aircraft Spruce



But honestly, I would like one that you can program to show the highest, and lowest temperatures all the time, and sound the alarm if there is a difference of more than 100 degrees or so. It looks like tha above gage can sound the alarm if EGT is too high, or too low, but what about difference between cylinders?

 

[SShafranko]

The only reliable way to know if an injector is going bad, other than a change in sound, is an EGT guage for every cylinder. Three regular guages, one for every 2 cylinders, would be great.

I also like this one:

AEROSPACE LOGIC CHT/EGT INDICATORS from Aircraft Spruce



But honestly, I would like one that you can program to show the highest, and lowest temperatures all the time, and sound the alarm if there is a difference of more than 100 degrees or so. It looks like tha above gage can sound the alarm if EGT is too high, or too low, but what about difference between cylinders?

Wow Great find. Thats a sik piece. But u need the thermocouple probe. How the heck would you pull that one off. Where would you mount the probe?(on the exhaust manifold?) I love that thing!!!!!!!!!!!!!!!!!!!!!!!!!!! Definitely buying that gauge.

 

[betterthanstock]

Wow Great find. Thats a sik piece. But u need the thermocouple probe. How the heck would you pull that one off. Where would you mount the probe?(on the exhaust manifold?) I love that thing!!!!!!!!!!!!!!!!!!!!!!!!!!! Definitely buying that gauge.

I think the one ending in P includes the probes (thermocouples). Why would it be more money? Call 'em in the morning and find out if the one for $ 571 includes the six probes.



On second thought, it looks like they sell hose-clamp style probes, which are too weak for turbo'd engines. You need good probes, that thread into the manifold, not clamped on.

see this for comparison:

EGT, exhaust gas temperature gauges, egt probes, egt bayonet probes, egt clamp style probes.

 

[cerberusiam]

The only reliable way to know if an injector is going bad, other than a change in sound, is an EGT gauge for every cylinder.

Maybe. IF the EGT change would register as being out of spec which you probably would not see if the gauge was on 2 cylinders and the exhaust mixing, or, IF the injector failed in such a way that it effected the EGT's.



Thats only one of the ways an injector can "fail" and one of the more infrequent ones. More often the injector just fails to inject adequately or it cracks and dumps fuel into the crankcase. Either may not and probably won't show on an EGT gauge.



Even a change in sound may or may not indicate a failure, but carbon deposits. Facts is there is no reliable way to tell if an injector has "failed" unless it is pulled and checked against operational specs. The best we can do is monitor EGT's, fuel mileage, oil level, and what is coming out the tail pipe, and last but not least GUESS there is a problem.



Anything more is just cool toys that give that placebo effect. :-laf

 

[betterthanstock]

Maybe. IF the EGT change would register as being out of spec which you probably would not see if the gauge was on 2 cylinders and the exhaust mixing, or, IF the injector failed in such a way that it effected the EGT's.



Thats only one of the ways an injector can "fail" and one of the more infrequent ones. More often the injector just fails to inject adequately or it cracks and dumps fuel into the crankcase. Either may not and probably won't show on an EGT gauge.



Even a change in sound may or may not indicate a failure, but carbon deposits. Facts is there is no reliable way to tell if an injector has "failed" unless it is pulled and checked against operational specs. The best we can do is monitor EGT's, fuel mileage, oil level, and what is coming out the tail pipe, and last but not least GUESS there is a problem.



Anything more is just cool toys that give that placebo effect. :-laf

Actually a cracked injector will dump fuel into the fuel return passage, to the fuel tank. The upper part, around electrical solenoid, is low pressure fuel, that flows back to the tank. Fuel gets into the oil by leaking continuously, and washing down the cylinder wall into the crankcase. I believe an EGT would catch that cylinder. That aircraft EGT gage that shows all six cylinders, would catch an off spec cylinder (of course it takes 6 probes, and a lot of $$), if it's too hot, or too cold. But, like I said, I wish it would be programmable to sound an alarm if there's a difference of let's say more than 100 deg either way. The dodge manual mentions that an overtightened connector tube, would bend the injector body, and possibly leak fuel into the combustion chamber, around the copper washer. I still think that extra fuel would affect the EGT.

Someone has to try one of these gauges out, and let us know how even (or not) the temps are.

 

[SShafranko]

Actually a cracked injector will dump fuel into the fuel return passage, to the fuel tank. The upper part, around electrical solenoid, is low pressure fuel, that flows back to the tank. Fuel gets into the oil by leaking continuously, and washing down the cylinder wall into the crankcase. I believe an EGT would catch that cylinder. That aircraft EGT gage that shows all six cylinders, would catch an off spec cylinder (of course it takes 6 probes, and a lot of $$), if it's too hot, or too cold. But, like I said, I wish it would be programmable to sound an alarm if there's a difference of let's say more than 100 deg either way. The dodge manual mentions that an overtightened connector tube, would bend the injector body, and possibly leak fuel into the combustion chamber, around the copper washer. I still think that extra fuel would affect the EGT.

Someone has to try one of these gauges out, and let us know how even (or not) the temps are.

I am definitely going to try this gauge. I am also going to probe each cylinder with the correct probes. I don't know much about this issue but for some reason common sense is telling me that the egt would change drasticaly in that particular cylinder whether it dumps more fuel or not enough. (Im usually wrong) But i am going to try it within the next month or two. I'll report back with findings.

 

[moonranch]

If all you need to do is find a cold or hot cylinder(but not know the exact temp), it would be cheaper to get an IR thermometer and check each exhaust port. Even if you had to do it on a dyno, it would still be cheeper.

 

[SShafranko]

If all you need to do is find a cold or hot cylinder(but not know the exact temp), it would be cheaper to get an IR thermometer and check each exhaust port. Even if you had to do it on a dyno, it would still be cheeper.

I'm talking about monitoring it while u are driving. If the injector goes while u are driving so that u can shut the engine down without doing extensive damage.