1990 Iroc swapped from a TPI with a carb setup. I'm having some issues with keeping a steady fuel pressure with my stock in tank pump and mallory regulator. I was thinking of going to a mech if I didnt get the issue resolved by the weekend.

QUESTION

If I do this, I will have to get a fuel pump pushrod, yes? Also would a TPI cam have the lobe on it for the mechanical pump? Provided that checks out, does the assembly slide in without much effort?

 

is your 90 block even drilled for a rod to go in it ?

does your cam have a FP lobe ?

if yes and yes then it should be simple

you are going to swap the electric sender unit for a mechanical one right ?

good luck

 

I actually went and looked back at my swap pictures and realized that my old cam had a lobe on it, so I would assume the new one did (the picture on summit shows that it does, although sometimes what you see isn't the same product #)

As for the hole in the block, I would assume it would be there. These blocks were relatively unchanged until the LT1 came along, correct?

As for the sending unit, I was going to use a hard line that was the right length, as opposed to rubber hose, in place of the pump.


All these things I think are just my assumptions, I just want to see if you guys could confirm it for me

 

Even in the newer Gen I blocks, they have the passage for the pump push rod drilled, even if the cam does not have a lobe. For instance, the ZZ4 I just got has the push rod hole, but the hyd. roller cam can't be adapted for use with a mechanical pump.

And I would assume that if your cam is a hyd. flat tappet, it has a lobe for the fuel pump, unless it was designed for a fuel injected engine. hope this helps,

 

I guess the best thing to do would be to pop the cover off and check before I get into it. If I take it off, is oil going to come gushing out?

 

If the engine is running, yes, but if the engine is off, only a couple of table spoons will come out. You will need a different cover for the mechanical pump, when you remove it for inspection, it might be a good time to change the cover out.

 

ive removed man,y and never had oil come out of it

its jut an opening in the side of the crankcase and wayyyy above the oil level

no reason for oil to come out of it

good luck

 

Wonder how my carb is getting fuel, then. I don't have an in-tank or any other electric pump, just the engine-mounted mechanical. . .


(For the record, the ZZ4 hydraulic roller cam has the mechanical pump lobe.)

 

Thanks guys. Nothing is set in stone yet, I wanna see if i can find out how to get my regular pump to give me a constant pressure with the regulator, because right now its not doing it. Maybe I'll wire up a manual switch to switch the in tank on when I want.

 

Sounds like your in-tank pump is going bad?

Make sure your block is bored completely for the pump rod. I've got a '99 crate motor that was not bored completely through for the rod. There's a few out there.

 

id check your timing make sure you set the timing with the vacuum advance off when i first started my car the fuel pressure went between 5 and 8 the timing was so off when you gave it any kind of gas it would backfire and die set the timing at 12 advanced and the pressure stays constant 5psi.

 

Na, its defiantly more complicated than that. But I just rigged the fuel pump through the relay so its working now. Now, however, I cant get the car to start when its warmed up, not even a sputter, even after only 2 minutes running, and still 7psi, but thats for another thread, haha.

 

I have had the same problem with my TPI pump and mallory... I have decided to go to stock mechanical....

For the record I had a LT4 hotcam with a fuel pump lobe.... incase you were wondering even the LT motors had the lobe. I have an LT1 cam right now with the lobe... +2 for hydraulic rollers

 

Fixed the issue guys. Before digging into a mech pump conversion, I tried the rigging of the relay and it completely worked.

 

The vortec block i have is machined for the fuel pump just not drilled. The lt1 cam i have does not have a fuel pump lobe on it. From what i understand most aftermarket cams have the lobe.