EFI conversion: the good, the bad and the ugly.

rocket dawg

Veteran Member
May 5, 2015
566
Grand Rapids Mi
The Holley kit tells you to use the same feed hose for the return line also. the pressure feed line did not leak after 5 turns of the key off and on. I think the return line pressure is higher than you think, but I will do my best to confirm.
 

krabben1

Veteran Member
Lifetime Gold Member
May 16, 2007
8,429
( . Y . )Delco
1.Is the neighbor chick hot?
2.I would(and did in my truck bed)just cut a neat square with a jigsaw,fine metal blade over the pump.Rivet an aluminum strip from underneath for a ledge for the piece you cut.Peen the rivets in as flat as you can.Throw a trunk mat in.You can either do a dab of silicone to secure the lid or something like that.
 

rocket dawg

Veteran Member
May 5, 2015
566
Grand Rapids Mi
Lol, she moved. I did find the return line pressure its 3 psi . Today I'll start the car with the gas tank still on the ground and see if there are any leaks. Then decide on an access door in the trunk. I looked into a replacement trunk floor pan that would match and lay over the access hole and they are priced higher than I thought.
 

70 1/2

Member
Feb 19, 2009
95
mpls MN
The tank is still in the car as of this morning. Gas is drained out, about 18 gallons worth. Siphon hose is very small so it takes about 25 minutes to fill a 5 gallon can. I was working on other stuff ( distracted) and the gas can over filled and down the floor drain it goes. Maybe a gallon. So out comes the degreaser and hose. I dont know what is leaking yet. Later today or tomorrow I'll know. The fuel pump has 6 or 8 small bolts with a gasket that holds it in and it has a return line. I'll have to look at my notes to find the part number. I routed the hoses so that I have enough to drop the tank with the hoses and wires still intact. So the plan is drop the tank, add some gas to it, turn key on and locate the leak. Yeah. I'm very hesitant to cut metal with all the sparks anywhere in that area. I believe this is the tank and pump kit:

Holley Sniper 19-140 - Holley Sniper EFI Conversion Fuel Tanks​

https://www.summitracing.com/parts/sne-19-140/make/pontiac/model/firebird/year/1979 The part number for the pump isnt listed with the tank kit. But I had to order just the replacement pump once. Summit figured that out.
I have enough hose so that I can cut it, install a new fitting ( if needed) and re install. Once a fitting is on the hose, its impossible to remove it w/o destroying it. A loose clamp or fitting is probably the cause. An access door sure would be nice at this point. The stock tank goes in and out fairly easy, this new tank seems a bit larger so I have trouble getting the strap bolts tightened up. 1/2 inch longer bolts may help this time. Overall, I like the Sniper EFI system, car runs great. The hand held screen died last year. Holley sent a new one free of charge. ( $308 cost) .
Sounds like you have my luck
 

zzfranczz

New Member
Jan 22, 2011
2
Los Angeles
Wow, thought it was just me who does things four times to get it done once. I am planning the same mod so I am watching. Be patient. I always tell myself that I am on the path to doing it right, no matter what the setback is. I always come back, push the frustration aside and think about what is the best thing to do in doing the job right. I only focus on one thing at a time. Good luck!
 

procharged81

Veteran Member
Nov 16, 2011
126
NE PA
Here's my situation. I've added Holley Sniper EFI and it's been good so far. If I had to do it again, I'd opt for the inline exterior fuel pump. My friend has this and it's a loud pump for sure, but it has its advantages. I installed a new gas tank ( 79 T/A sbc 400 mota ) designed for the in tank fuel pump and I've had my issues with it. I over tightened the fittings and cracked a $300 plus fuel pump= leak ( my fault) dropped gas tank. Next time I was gun shy and didnt tighten enough= leak another gas tank drop. Fuel line routing problems and pinched fuel lines- tank drop and hammer the trunk floor up in a few areas for added clearance. These gas tanks dont leave any wiggle room. Fast forward 1.5 years and everything has been good. I fire the car up this week after storage and gas leaking on the floor when car is running. WTH! Yet another gas tank fuel pump issue. When I have the tank out this time, I'm thinking about cutting an access panel in the trunk floor. Has anyone done this? If so , post some pictures. thanks. Going out to siphon gas yet one more time.
I’m using the Holley 12-890 external pump, not mounted to the frame, but an isolation bracket, which is then mounted to frame. ZERO noise, you would never know it had an electric pump. Prior to the bracket I made, it was mounted under trunk, in behind the rear….it would vibrate out any fillings you might of had in your teeth.
 

krabben1

Veteran Member
Lifetime Gold Member
May 16, 2007
8,429
( . Y . )Delco
I’m using the Holley 12-890 external pump, not mounted to the frame, but an isolation bracket, which is then mounted to frame. ZERO noise, you would never know it had an electric pump. Prior to the bracket I made, it was mounted under trunk, in behind the rear….it would vibrate out any fillings you might of had in your teeth.
Pic. Of. Bracket. Please.
 

rocket dawg

Veteran Member
May 5, 2015
566
Grand Rapids Mi
The pump mounting plate has 6 holes in it. It would be better with 12 holes. The way its designed, the pump can be turned/mounted in 60 degree increments , which is too much. The new gas tank has 6 holes, so the pump can be mounted in any direction( 60 degree) Just adding another 6 holes would bring it down to 30 degrees. A person could drill the extra 6 holes. I would hope Holley has this figured out by now. The pump hit the trunk floor pan, at least the clamps on the hoses did. On the Gen 2 replacement tank that is. Very little room between tank and trunk. I did cut an access hole in the trunk and Im happy I did. The pressure hose was somewhat kinked, not completely but about 75% restricted. There would have been no way to tell w/o the access door. Again a 12 hole pump flange would have helped here. As is, Rotating the pump to the next set of holes would have aimed both pressure and return line towards the transverse muffler with the 6 hole pump. Not good. If you dont have a transverse muffler, this becomes a non issue. After the tank was reinstalled, a buddy tells me I could have borrowed his ATV/Motorcycle lift which is perfect for a gas tank install especially when there's 3 gallons of gas in the tank sloshing back and forth. So far no leaks. But I've been in that boat before. Leaks popped up after a few weeks but in this case after 1.5 years. The access hole is twice as big as needed. But everything-- pump/ fuel level sending unit, vent lines and all the hoses can now be worked on with tank in the car. There is also enough room to add a heat shield between the hoses and muffler/ The muffler already has a heat shield, but an extra one cant hurt. The return line doesnt have to be the expensive pressure line. The return line at the throttle body should be the flexible pressure line but under the car it can be anything. I've had my issues with this design but I would not go back to a carburetor. The car runs great.
 

procharged81

Veteran Member
Nov 16, 2011
126
NE PA
Pic. Of. Bracket. Please.
40FF1F23-7887-425E-902C-B122FFC3101D.jpeg


I’m away over seas for work right now, so I can only draw you a quick sketch and post the only picture I have on my phone.

We have the stock muffler that goes in front of the gas tank to thank for this handy mounting.

The muffler is hung by a mount on each side of the trunk, that is attached to the under side. I cut two, 4” long pieces of 1/8” thick, 3/4” wide flat stock, and drilled a hole towards the ends to run a bolt through and secure to the provided hole. Then used 3/8” round bar (over kill, but that’s what I had) to heat till red, and make bends I was looking for…(see diagram). This bar is then welded to the 2 pieces of flat stock that was bolted to the original muffler hanger mounts. I then took 2 more pieces of the flat stock, just big enough to mount the pump to, and welded them to the round bar.

What I found was easiest to mount pump, was to bolt the plates to the pump, then put the pump (with plates bolted to it) up to the round bar that was mounted to the car. This way I could get the best angle/position of the pump without making a mess of any line routing. Mark the plates and round bar carefully with paint marker. Remove everything and tack the plates to the round bar with pump attached (this will keep your bolt hole spacing). Remove pump and burn everything together solid.

My pump is hung upside down, so I used bolts with safety wire so I don’t have to worry about bolts coming out and having the pump dragging on the road behind me.

As it sits, you can’t see the pump hanging below the tank, and the fuel gravity feeds to the pump.

2 other guys in my area were so impressed with how quiet the pump was, they re-did their pumps and lines the same way I did mine.

Paint/powder coat to color of your choice, and enjoy the quietness.

Took me about an hour…I have a lift. On your back will take longer, but well worth it.
 

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wiseryder

Veteran Member
Lifetime Gold Member
Sep 11, 2004
2,318
Michigan USA
View attachment 137684

I’m away over seas for work right now, so I can only draw you a quick sketch and post the only picture I have on my phone.

We have the stock muffler that goes in front of the gas tank to thank for this handy mounting.

The muffler is hung by a mount on each side of the trunk, that is attached to the under side. I cut two, 4” long pieces of 1/8” thick, 3/4” wide flat stock, and drilled a hole towards the ends to run a bolt through and secure to the provided hole. Then used 3/8” round bar (over kill, but that’s what I had) to heat till red, and make bends I was looking for…(see diagram). This bar is then welded to the 2 pieces of flat stock that was bolted to the original muffler hanger mounts. I then took 2 more pieces of the flat stock, just big enough to mount the pump to, and welded them to the round bar.

What I found was easiest to mount pump, was to bolt the plates to the pump, then put the pump (with plates bolted to it) up to the round bar that was mounted to the car. This way I could get the best angle/position of the pump without making a mess of any line routing. Mark the plates and round bar carefully with paint marker. Remove everything and tack the plates to the round bar with pump attached (this will keep your bolt hole spacing). Remove pump and burn everything together solid.

My pump is hung upside down, so I used bolts with safety wire so I don’t have to worry about bolts coming out and having the pump dragging on the road behind me.

As it sits, you can’t see the pump hanging below the tank, and the fuel gravity feeds to the pump.

2 other guys in my area were so impressed with how quiet the pump was, they re-did their pumps and lines the same way I did mine.

Paint/powder coat to color of your choice, and enjoy the quietness.

Took me about an hour…I have a lift. On your back will take longer, but well worth it.
I'm curious, what you doing oversea's for work,
 




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