TBI running on a mechanical pump

[dyeager535]

Couple of things.

If you can't easily access the side of the block (like when it's sitting on an engine stand) you may not find out that it won't clear the block except after the unit cracks as you thread it in. Or you get a leak thinking it was threaded in, when it was actually hitting the block and not fully tightened. To install that switch/sender down low, it requires an extension, otherwise the switch/sender body contacts the flared out portion of the block above the oil filter.

FWIW, without the proper distributor, your injectors aren't going to fire.

Also, the linked thread with the oil pressure switch. I'm getting to the point that I'm not trusting of the unit anymore, like the original poster in that thread. I've had two of them fail in the last ~10 years, and these are Delco units. Normally not a huge deal since the relay normally takes care of it, however the last one failed with the switch closed, which ran the fuel pump with the key off.

On TBI I'd be tempted to not use the switch/sender combo. You already have a very easy way to bypass the relay (the red wire dangling off the fuel pump relay connector). I like the concept of all-in-one, however it's of minimal value in the TBI setup IMO, and it just means you have to replace a more costly piece, with twice as many failure modes.

 

[Larry]

I tried one of these mechanical Racepump.com pumps back in 2007 when I did a Marine L29 MPFI intake on my 454HO, which ran on an MEFI ECM and required 42 psi pressure like a Tune Port engine. I never actually got to drive it on the street other than a couple test drives but it seemed to work okay to other than it would never stop leaking and loosing prime. The people at Racepumps were super nice and tried to be as helpful as possible but in the end, I just returned it to them out of pure frustration and went to an electric pump. Those pumps were pretty new in 2007 and had known teething issues as found all over various forums back them. All the problems seemed to be related to my exact issue of leaks at the piston that actually protruded out of the pump body and loosing prime. I think they are out of business now, which is too bad as the idea was great

 

[6872xtc]

The 2 different variations of fittings that I have found in trucks. One is 1/4" to 1/4" the other is the 1/4" to 1/8"

 

[dyeager535]

What was the stock location of the three wire switch/sender on the R/V trucks?

I want to say all the ones I have are 1/4" thread, but I suppose they could have made them in 1/8" too.

I should have clarified....I was talking small block with the fitment issues.

 

[6872xtc]

What was the stock location of the three wire switch/sender on the R/V trucks?

I want to say all the ones I have are 1/4" thread, but I suppose they could have made them in 1/8" too.

I should have clarified....I was talking small block with the fitment issues.

The back of the block by the intake. This is my spare '90 Blazer with the transmission. The transmission is out, which is why it is so light beyond the fitting and sender.

 

[Chevy305]

From what I'm reading, I'm thinking I won't bother to install the oil pressure switch at first. I'll see about finding the upright 90° to adapt it to the port at the back of the valley.

 

[Chevy305]

Couple of things.

FWIW, without the proper distributor, your injectors aren't going to fire.

I've been reading up on TBI swaps in things other than small blocks and the ECM will still fire the injectors if it gets a tach reference signal from the distributor which is the Purple/white wire at the TBI distributor plug. So take the coil - tach signal off the HEI and connect it to that wire with a filter to smooth out the pulse. This way the ECM sees the rpm signal and fires the injectors accordingly.

 

[dyeager535]

I've been reading up on TBI swaps in things other than small blocks and the ECM will still fire the injectors if it gets a tach reference signal from the distributor which is the Purple/white wire at the TBI distributor plug. So take the coil - tach signal off the HEI and connect it to that wire with a filter to smooth out the pulse. This way the ECM sees the rpm signal and fires the injectors accordingly.

If you have the proper wiring at the distributor, why not just stab the right distributor in there to fire it up? Seems like more hassle to rig up the wires (and those are small terminals) than it would be to just stab the distributor.

FWIW I swapped my distributor a couple months back ($55 cheapy off rockauto), and it was real easy, fired up immediately. Remove cap, note position of rotor (I rotated the engine so rotor was pointed someplace easy to associate it with), remove old distributor, stab new distributor in, connect wires (except EST bypass) fire it up. Time it to zero, turn off, reconnect EST wire, start engine.

 

[Chevy305]

If you have the proper wiring at the distributor, why not just stab the right distributor in there to fire it up? Seems like more hassle to rig up the wires (and those are small terminals) than it would be to just stab the distributor.

FWIW I swapped my distributor a couple months back ($55 cheapy off rockauto), and it was real easy, fired up immediately. Remove cap, note position of rotor (I rotated the engine so rotor was pointed someplace easy to associate it with), remove old distributor, stab new distributor in, connect wires (except EST bypass) fire it up. Time it to zero, turn off, reconnect EST wire, start engine.

The problem is that the timing tab doesn't line up with the balancer so I'd need to figure out a proper TDC mark to set the timing. So in the interest of getting my plow truck back up and running, I'm just going to leave the HEI in place for now.

 

[Kain]

what is the brass piece called and where can you get it thats not 65 dollars

 

[campfire]

From what I'm reading, I'm thinking I won't bother to install the oil pressure switch at first. I'll see about finding the upright 90° to adapt it to the port at the back of the valley.

Is there something special about the 90* elbow? For my rig I just grabbed a street elbow from the plumbing section of my local hardware store. I know mine is a diesel, but the accessory configuration is closely patterned after the 350.

 

[campfire]

Anyone mention there would not be a priming cycle either?

Did anyone think that the variable pressure would play havoc with the injector fueling, since it's nowhere near high enough to keep the fuel pressure regulator happy?

 

[bp71k5]

From what I'm reading, I'm thinking I won't bother to install the oil pressure switch at first. I'll see about finding the upright 90° to adapt it to the port at the back of the valley.

I’ve been running without the switch for almost 10 years. I guess it would be bad to loose the fuel pressure if the truck was in a spot where the engine dying would be dangerous, but it’s been worth the simplicity so far.