PisaturoJr
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Fuel leak under intake manifold. Injector pump seems OK. Truck starts & runs perfect. Leak is pretty bad. Leave a trail down the street.
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Bad fuel leak under intake manifold.
- Thread starter PisaturoJr
- Start date
Will L.
Well-Known Member
Not a fun day, but replace all the rubber line with sae30r9 & new clamps if you see it is the he fuel lines
The original rubber can’t withstand the ethanol in the new diesel fuel.
Other option is the ffm (fuel filter manager) is leaking- kost common there is the fuel heater oring. Unbolt it and raise it up to see.
There is a ton of upgrades to do there while at it if you’re interested but thats the basic things to check
The original rubber can’t withstand the ethanol in the new diesel fuel.
Other option is the ffm (fuel filter manager) is leaking- kost common there is the fuel heater oring. Unbolt it and raise it up to see.
There is a ton of upgrades to do there while at it if you’re interested but thats the basic things to check
PisaturoJr
New Member
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Thanks, Will give it a try. Surburban has 296 K miles. I am 83 & at my age i do not want to buy another truck. Had the 99 surburban since 20000. It had 65K on it wheni bought it.
Big T
Well-Known Member
Will’s suggestions are spot on. Only additional I can add is to check for leaks with a flashlight in the dark. The diesel fuel will reflect and shimmer in the light and you will find the source of your leak.
PisaturoJr
New Member
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Thanks, will give it a try.
MrMarty51
Well-Known Member
Get the intake manifold removed.
By pass the fuel pump relay switch then watch where the fuel is flowing from.
The ignition switch can be turned to the run position and the lift pump will run momentarily, if You, or a helper is watching You most likely will be able to see where the leak is at.
Just do not turn the switch to the run position. If fuel would leak into the intake ports that would create a run away engine affect.
I built a bracket for the FFM on My engine, then, routed all but the WIF drain hose above the manifold.
I’ll get a picture soon as I get out to the shed.
By pass the fuel pump relay switch then watch where the fuel is flowing from.
The ignition switch can be turned to the run position and the lift pump will run momentarily, if You, or a helper is watching You most likely will be able to see where the leak is at.
Just do not turn the switch to the run position. If fuel would leak into the intake ports that would create a run away engine affect.
I built a bracket for the FFM on My engine, then, routed all but the WIF drain hose above the manifold.
I’ll get a picture soon as I get out to the shed.
Will L.
Well-Known Member
I believe he meant don’t put the key into the start position. You need the run position for that he lift pump to operate.
A good way to do that yourself- before removing the intake manifold it is smart to disconnect the negative side battery cables. This should be done anyways.
When you are ready to watch for the leak, first go put the key into the run position- not start. Then go connect one of the ground cables to the battery. As soon as you do it the lift pump will turn on.
There is one place to watch for that is hard to see and we are all hoping isn’t the situation: If you are familiar with how the weep hole on a waterpump is that indicates a bad front seal in it… The injection pump has one that works the same way. There is a small hole, maybe 1/8” diameter iirc on the bottom front area of the injection pump. When fuel leaks out of there it is because the foreward seal is bad and requires the injection pump rebuilt to replace it.
An inspection mirror is often required to see it leaking out of the hole.
However the most common leak is the one we are all hoping for is simply the 5/16 fuel line that goes from the fuel filter to the injection pump.
All the “rubber” fuel line should be replaced with sae30r9 to withstand the ethanol in our diesel fuel nowadays. The only exception that is the 6” piece that is coming out the front of the injection pump in an upside down “U” shape -the return line. It is 1/4” diameter. For that you want clear tubing for easy diagnosis in the future for air intrusion, contamination, etc. Fuel-line.com sells it rated for the fuel- it just doesn’t have the abrasion resistance but there is nothing that will rub in it in this location.
A good way to do that yourself- before removing the intake manifold it is smart to disconnect the negative side battery cables. This should be done anyways.
When you are ready to watch for the leak, first go put the key into the run position- not start. Then go connect one of the ground cables to the battery. As soon as you do it the lift pump will turn on.
There is one place to watch for that is hard to see and we are all hoping isn’t the situation: If you are familiar with how the weep hole on a waterpump is that indicates a bad front seal in it… The injection pump has one that works the same way. There is a small hole, maybe 1/8” diameter iirc on the bottom front area of the injection pump. When fuel leaks out of there it is because the foreward seal is bad and requires the injection pump rebuilt to replace it.
An inspection mirror is often required to see it leaking out of the hole.
However the most common leak is the one we are all hoping for is simply the 5/16 fuel line that goes from the fuel filter to the injection pump.
All the “rubber” fuel line should be replaced with sae30r9 to withstand the ethanol in our diesel fuel nowadays. The only exception that is the 6” piece that is coming out the front of the injection pump in an upside down “U” shape -the return line. It is 1/4” diameter. For that you want clear tubing for easy diagnosis in the future for air intrusion, contamination, etc. Fuel-line.com sells it rated for the fuel- it just doesn’t have the abrasion resistance but there is nothing that will rub in it in this location.
jrsavoie
Recruit
On a 1999 there should a spade connector hanging out of a big wire loom, behind and below the underhood fuse box. Between the fuse box and the firewall.
It can be hard to see and sometimes got tucked back in the loom.
You can power that connectors to run the lift pump. I always installed a safety toggle switch there to run the lift pump for diagnosis and priming.
One 5/16 eyelet, 1 inline fuse, safety toggle switch, spade connector. Heat shrink or just use heat shrink connectors. a short piece of wire.
A lot nicer than jacking around getting in and out of the vehicle. Especially when you're all dieseled up and stinky.
It can be hard to see and sometimes got tucked back in the loom.
You can power that connectors to run the lift pump. I always installed a safety toggle switch there to run the lift pump for diagnosis and priming.
One 5/16 eyelet, 1 inline fuse, safety toggle switch, spade connector. Heat shrink or just use heat shrink connectors. a short piece of wire.
A lot nicer than jacking around getting in and out of the vehicle. Especially when you're all dieseled up and stinky.
Paveltolz
Доверяй, но проверяй
jrsavoie
Recruit
It's often down lower and harder to see.
Thanks for the pictures.
It's very easy and cheap to add a toggle switch right there