Engine/Transmission (1994 - 1998) 12 valve lift pump replacement

[JohnCollier]

Pump is leaking around rubber boot, maybe from plastic plunger. I understand about using studs and some articles talk about making sure the engine is set to not have so much pressure on the lift pump rod. How do i do that? Some articles say to reuse the old pump rod, any recommendation on that? Thanx

 

[Signal73]

So you should bar the engine over so the lobe on the camshaft that actuates the lift pump plunger is at the low point by using a barring tool, turning the alternator opposite of engine rotation, or removing the bellhousing inspection cover and use a flathead screwdriver against the bellhousing on the flywheel ring gear. Those are in the order id prefer to turn the engine over. Some say use one of the bolts that hold the dampener on the crankshaft but that can be sketchy and if you snap a bolt you’re going to be sorry.

So how do you know the lobe is at its low point? Remove the fuel lines from the pump. Loosen the 2 bolts holding the original lift pump about 1/4” or slightly more. Note the tension on the bolts. If the lift pump wiggles you’re probably already at the low point. If the bolts seem to have tension rotate the engine until the pump seems free. Then you should be at the low point. Having a helper makes this go a lot easier. Have them bar as you manipulate the pump.

With that done the need for studs is no longer.

The lift pump I bought came with a new plunger so that’s what I used.

 

[Signal73]

The skinny one is the lobe you are dealing with. Note there is not much lift so low to high spot is not that great of a distance.

 

[JohnCollier]

So you should bar the engine over so the lobe on the camshaft that actuates the lift pump plunger is at the low point by using a barring tool, turning the alternator opposite of engine rotation, or removing the bellhousing inspection cover and use a flathead screwdriver against the bellhousing on the flywheel ring gear. Those are in the order id prefer to turn the engine over. Some say use one of the bolts that hold the dampener on the crankshaft but that can be sketchy and if you snap a bolt you’re going to be sorry.

So how do you know the lobe is at its low point? Remove the fuel lines from the pump. Loosen the 2 bolts holding the original lift pump about 1/4” or slightly more. Note the tension on the bolts. If the lift pump wiggles you’re probably already at the low point. If the bolts seem to have tension rotate the engine until the pump seems free. Then you should be at the low point. Having a helper makes this go a lot easier. Have them bar as you manipulate the pump.

With that done the need for studs is no longer.

The lift pump I bought came with a new plunger so that’s what I used.

Thanx, that helps

 

[JMcCoy]

That's way too complicated. Longer studs will make it super easy. No need to bar the motor over. If you feel the need to do so, just bump the starter. K.I.S.S.!

 

[Hootguy]

unless you have a mint truck,do yourself a big favor,and remove the plastic inner fender,cut a nice even knotch out of the steel fended liner in front of the lift pump.now you have acces to sit nicely in front of the wheel well and change the pump at arms reach,the plastic inner fender will hide that notch once replaced,make replacing a pump a 15 minute deal.and no need to contort your arms trying to do it from above or below,

 

[GAmes]

 

[Joseph Donnelly]

I re-use the old rod if in good shape since it is mated to the cam lobe, similar to lifters mating to cam lobes. I usually pot a dab of moly cam lube on it as extra insurance.