New life in the '94 Yukon

[SgtPreston]

Well, it's finally finished - replaced the original drivetrain (5.3 Tbi and tranny) with a new crate motor from Blue Print Engines and a 700 R4 tranny from Phoenix Transmissions. It's rated at 365 HP but dyno-ed at 376 and is equipped with a Holley Sniper EFI.
I've got about 300 break-in miles on it at present and it's really running smooth (relatively smooth as it has a mild cam) and a big difference in power from original. It does require premium gas so I'll be driving it sparingly, or adding octane booster - sticker shock the first time I filled the 30 gal. tank - but I still plan to enjoy it.

 

[SgtPreston]

Well, it's finally finished - replaced the original drivetrain (5.3 Tbi and tranny) with a new crate motor from Blue Print Engines and a 700 R4 tranny from Phoenix Transmissions. It's rated at 365 HP but dyno-ed at 376 and is equipped with a Holley Sniper EFI.
I've got about 300 break-in miles on it at present and it's really running smooth (relatively smooth as it has a mild cam) and a big difference in power from original. It does require premium gas so I'll be driving it sparingly, or adding octane booster - sticker shock the first time I filled the 30 gal. tank - but I still plan to enjoy it.

Okay, here's an update - The Holley Sniper is being replaced by an Edelbrock 1406 4BBL! I ended up being stranded twice and the second time was made worse by no-shows from AAA. I didn't do enough research on the Sniper before buying - it seems they have the ECU on the front of the unit and it is very susceptible to EMI (electro-magnetic interference) and RFI (radio frequency interference). One video on installation suggested (depending on the age of components) you should consider shielding the alternator, distributor, coil and using radio shielding plug wires.
I have a new Kenwood multi-function radio and I noticed when I started the truck the radio would come on for 5 secs, then go off for about 10 secs before coming back on and staying on. Obviously the signal must have been interrupted by the Sniper computer going through it's calibration/startup phase. The first failure was a bad relay (so we thought) - replaced the relay and it seemed to solve the problem - this was on Thursday, but the truck shut down again on Saturday so it is in the shop for trouble-shooting this last failure. Symptoms were the same so I'm assuming the electric fuel pump lost power from the relay - doesn't really matter what the cause was, the Sniper system is history.

This second failure was made doubly bad by AAA being unable to get a tow vehicle to me I called 4 times Saturday afternoon (3:30, 4:30, 5:30 and 6:30) and each time was told the dispatcher would contact the provider and they would advise me of their arrival time - didn't happen! So I canceled the call, left the truck (Wife had to drive an hour to pick me up - not good) and went back on Sunday (Father's Day) and called AAA again - same story, but after an hour and a half I finally got a "supervisor" and she called the provider direct - Sorry, they had no one available that day! Instead of trying to locate an alternate provider, the supervisor said I could locate one and she would send me forms to get reimbursed for the tow service since AAA had no one available. Needless to say, AAA and I are not on very good terms right now.

 

[SgtPreston]

Well, time to eat a little crow - we dropped the tank to swap the 60 psi electric fuel pump for a 12 psi pump for the 4 BBL and found the little 4" long piece of tubing from the pump over to the pickup point had ruptured. It was supplied with the Holley pump for the ****** system and should have been good for in-tank service - possibly had a blemish?? No explanation but we decided to go back with the known correct hose and give the ****** another chance since this was not a failure of the EFI. The jury is still out but will keep you posted.

 

[OR VietVet]

Can't wait to see what was blocked this time! " And the hits just keep on comin' "!

 

[SgtPreston]

Apparently it was the commercial name given to the aftermarket EFI manufactured by Holley.

 

[willxfs]

This is interesting! Please keep us posted on how things worked out. Thanks!

 

[SgtPreston]

Okay, it's been sufficiently long enough since we replaced the small rubber hose connecting the fuel pump to the pickup and all things are still go - swapped out the break-in oil (500 mi.) and have about 200 more with no issues. EFI computer seems to be "learning" as it is supposed to - there are quite a few parameters for it to check but keeping my fingers crossed, all is well so far.