86 Comp EFI Install

OK guys. It’s time to face the critic’s. This is what I’ve be working on this winter. I found a 1986 HO Mustang to rob all of the EFI from. I started her up for the first time this weekend. Took her out for a shake down run today. I stopped & checked the plug color starting @ 2000,3000,3500,4000 & 4600 WOT all is good. I plan on checking the plugs some more next time out. It’s cold on the Columbia river this time of the year. I was going to post pictures but someone has changed something. And where did my picture album go?

Cool, How did you get the o2 to work. Details I would like some details.
What fuel pump did you use. Did you put an oil pressure switch in to kill the fuel if the eng dies.


Is this a mass air flow or speed density system.

I'm not going to use o2's. By not using them the computer will stay in open loop mode. The stock PCM EFI GT 40 run's this way. The computer will use it's internal A/F mapping program. If I find that the system is running rich I can install o2 simulators to cut the fuel back a little. From what I have found out the o2 are used just to fine tune A/F mixture leaning the mixture as need to get to 14.7 A/F mixture. I used a elect. pump from NAPA it run's up to about 90 lb the system bleeds any pressure over 37 lb back to the tank. I had not thought about a oil pump switch there wasn't one on the mustang. I wonder if installing a oil pressure switch would slow the start up.
Can anyone tell me how to load Pic. from my computer. the pic size is only 86.0 kb.

It might get a little complicated but Gm uses a temperature switch to run the pump if the eng is cold then it will automatically switch to oil pressure switch once the eng is warm.

The only reason I ask is in the event of a fire it would be nice to kill the fuel.

The o2 does do the fine tune on the fuel map sort of. If it stays on the lean/rich limit for to long the ecm will make a course adjustment then read the o2 for fine adjustment within the parameters of that course setting.

Attachment 11823Attachment 11824Attachment 11825Before & after

looks great, cant wait to find out how it performs for you

Cool mod! I haven't seen a battery there, before.....

Dare to be different... I hope it runs as sharp as it looks.

I second needing a method for the fuel pump shut off - 2 years ago we couldn't put out an engine fire on an open motor jet boat after two fire extinguishers and wet towels. That is, until somebody realized the key was still energized & fuel pump kept feeding the flames. Key off - fire out.

What intake manifold did you use...was it from a 351 efi F-150?

Looks great, nice build. Interesting to hear about performance.

That intake is off of a 86-93 Mustang 5.0 at least the upper is... The lower should be 351 specific. These are a dime a dozen... I will tell you that you don't want your AFR at 14.7 at WOT or under a big load. That is way lean. You will want your AFR at or under 14. My main hobby is racing Mustangs.

As much mustake stuff as there is out there surely you can find a programmer that will let you play with the fuel map.

I think there is one out there that will work from a smart phone.
A blue tooth adapter in the data plug links up to your phone no wires out in the open and you can adjust it on the fly.
http://www.latemodelrestoration.com/...ner-Programmer

I used a 1988 truck lower manifold a BC Bronco manifold adapter & a 1986 Mustang 302 HO upper manifold. When I started this project , manifold height was a concern of fitting under the dog house . The total height ended up being less than the stock flame arrestor. Oil pump switch is a on brainier idea I should have thought of it . Thinks 86 Century. I agree with the A/F ratio needing to be richened . I have just started looking for someone to help me with having a custom chip burnt . Any ideas of who it contact ? Also I need a flame arrestor that is under 3” thick that has a 3” flange . It would be grate to find one from a stock GT 40 motor.

I can't help with the flame arrestor .

You should be able to find a programmer that will let you make your own changes on the fly. Would be a bit more hassle to get set up but with a little tinkering the system will run at peak efficiency for every thing you want to do.

Since you could play with the mixture with some time the mix will be perfect for your eng. at the crazy loads we put on marine power plants.

OK guys the EFI project is completed. I’ve learned a lot about EFI in the process. End result is the top end is the same. Cold starting is instant. Hot start up is a touch of the key. Idle is more stable. Throttle response is incredible. Stab the throttle full, the engine takes a breath of air and the boat jumps out of the water in not much more than a boat length. We have been out twice skieing so far this spring and my ski buddy’s and I think that the pull is more constant than before. And the PP is confirming this. The end cost was about $800 and I lost track of the time involved. So what it was a winter project.

have you noticed any difference in fuel economy?

How about a detailed parts list so we can all go junkyarding!!

So far I’ve been stabbing the throttle a lot running WOT testing A/f . So know idea of the fuel usage .
Parts list…
All of the EFI from a 1986 302 HO Mustang 87 & 88 think are the same but don’t quote me. The HO 302 is the same firing order as the 351.
Lower distributor $45 & lower manifold $75 (round port) form a 351w,manifold adaptor form BC broncos $110, Elect fuel pump from Napa $95, a new heated o2 sensor $33, a 400 ohm resistor in line to the water heat sensor $3, a adjustable fuel regulator $75, air fuel gage to check the R/F ratio $50 or you can just check the plug color, and a power relay switch with a fuse to turn on all of the EFI.
Delete the EGR manifold remove the sensor form it and plug it in to the harness.

This last weekend we went skiing Friday & Saturday. The boat ran 2.6 hr cursing @ about 28 mph, 7 skiing pulls 34.2 mph & 2 bear footing pulls 39 mph on 7.1 gallons of fuel.

Attachment 12141Attachment 12142I ended up installing a o2 sensor into the exhaust. It ended up not being that hard. It turns out that cast iron is easy to drill and tap. I started by using a 1” copper pipe cap for the fitting that goes through the water jacket. I drilled a hole that was the same size as the outside diameter of the pipe cap & then finished fitting the hole with a dermal . Then I drilled and taped threads into the inner exhaust. The copper cap was installed using a spark plug gasket/ washer coated with high temp silicon to the inner exhaust and 5200 calk to the outer water jacket. So far I have logged 15 hrs with on problems.Attachment 12143

That's just friggin cool!

do you have your battery mounted in the dog house?

Its the second battery.

Yes I'll sell the carb. What's it worth? 5 years new,about 400 hrs. T T.

A rebuilt bench tested unit is $270. This is marine version correct?

Let me know if you want to sell it if not I'm going to be ordering one next week

$270 is a grate deal. If I were you that's the way to go. I got this carb new for about $500 and I thought it was a good deal. Good luck

Sorry Ben
I've been dealing on a 86 sunsport for over a year. It is going to be a complete rebuild. Talked the guy down to $400 yesterday. I'm not going to sale any of mt parts till the boat is dun.

ok man you have me sold on this project .. do you have any links for the spacers and such and you said 86 ho 5.0 lower or upper ? and has the sealant held up on the wet exhaust??

man this is awesome !!

You can get the adapter form BC Broncos. 351 lower with 302 upper manifold. So fare I’ve put about 20 hrs on the boat sense the o2 was installed. It’s working just fine. You will need to use a porting tool when you do the manifold install to make the ports match up exactly,. It took me about a hr.

Very interested in converting my sunsport to EFI. What did u do for the throttle cable and the shift cables?

Bump for question above.


Sent from my iPhone using Tapatalk

Attachment 13696Attachment 13697Attachment 13698Attachment 13699 For the throttle I made a bracket & riveted it to the existing throttle mount that is the same length as the carb cable mount. I made a new cable hold mount to line up with the throttle body. There is no need to change anything with the shift cable. If you are serious about doing this I have to tell you it will ,will, will take a lot of time, time, time.. For me making the change to efi was a challenge to see if I could do it. I would not recommend this change to anyone. But Good luck I will help you if I can.

Thanks a bunch for the info and the good pictures