EFI on 4-banger

[Mastiff]

Any suggestions on injecting an old 152ci 4-banger? I only want to do it if I can keep it pretty cheap, and I want it to look right. The stock carb is tiny and the intake is barely bigger than a silver dollar. I'd like to find a throttle body that doesn't require a ridiculous neck down. I just read that a 7730 ECM can work for single barrel applications... not sure what the best bet is for throttle body? I have an MSD ignition on this vehicle and I'd be happy just to use the EFI for fueling. Can the MSD trigger signal trigger the ECM?

[Six_Shooter]

The 152 is based on, or same family as the Iron Duke, correct?

If that is the case look at the mid '80s Celebrities and Fieros, for the intake manifold and TBI system, I'm sure there are other vehicles as well.

You won't use the MSD to trigger the EFI, but it can be retained. What you will do is replace the dizzy, with one that uses a 7 or 8 pin ICM (Ignition Control Module) so that the ECM not only knows that the engine is running and at what RPM, but also allow the ECM to control timing. You will then connect the MSD box as you would for any points trigger, where the white wire triggers the box and that drives the coil.

[EagleMark]

It was a 1227730 ECM for 2.5L one barrel TBI, not sure how big they are or if there are different sizes? Or if adapters are available?

You can also use an under hood 1227727. It is identical ECM in a weatherproof case. Lots of room under hood in them older Scouts, none in behind dash!

Although I have never done this with MSD box like 6a it is a recommended option from aftermarket companies like AFI. I have looked at schematics and it does have proper square wave form needed by ECM to work properly without burning up ECM.

I know you've done conversions before so you know most things that need to be done. Issues with old vehicles is fuel feed and return line fitting, problems specific to old scouts is crud in old rusted tank so a new tank or good cleaning and coating inside if structurally sound is in order, good grounds all back to motor block, and one that causes issues is the charging system on older vehicles just isn't up to par for keeping a good 12+ volts at idle, once off idle they charge real well so may think about a newer alternator swap before or during.

HTH!

[EagleMark]

The 152 is based on, or same family as the Iron Duke, correct?

No it's a half a IH V8 motor, literally.

[1project2many]

The "Model 700" throttle body injection unit has a similarly sized bore ( 45 - 47mm) and would be appropriate for a stock power level engine. It's found on various throttle body injected GM four cylinders from 87 to 91.
http://home.comcast.net/~fierocave/tbi700-2.htm
http://www.chalnet.net/Fiero/700%20Series%20TBI.doc
http://www.carburetion.com/pdfs/injectors_tbi.pdf

[gregs78cam]

I have the single TBI and air cleaner off of an '84 Sunbird I used to have, I may also have the ECM for it. But if you are doing a conversion I would say just upgrade to a '7427.

[Mastiff]

Thanks for the ideas. This Scout has been totally rebuilt. The tanks are new. That brings up a question though, how do you deal with dual tanks with fuel injection? Could an in-line pump after the switch work reliably?

[1project2many]

If you're running low pressure TBI then you can use a switching valve from an R/V truck with TBI. For high pressure systems I've always thought the low buck solution would be low pressure in tank pump feeding high pressure inline after the switch valve.

GM had a system in 95 or 96 with the high GVW one ton which used a second tank to supply the primary tank. Whenever the primary tank level dropped to 1/4, the pump in the secondary tank would turn on and pump fuel to the primary until the primary was full or until the secondary was empty. Unfortunately GM decided to wire both sending units in parallel to one gauge so there was no way to tell how much fuel was in either tank separately.

[Mastiff]

Sounds like a pain. The Scout tanks are a nightmare anyway. They won't fill from any modern fuel pump without overflowing due to the sharp bend in the filler and poor venting. I've been seriously thinking about switching to some sort of generic fuel cell type thing that I'd just put in the back (I have no top anyway). Anyone know if Summit or someplace has sending units for fuel cells that would take an in-tank pump with pressures appropriate for TBI?

[gregs78cam]

You could just get any fuel cell that would fit well and do the fuel pump upgrade listed here:

http://www.gearhead-efi.com/Fuel-Inj...l-Pump-Upgrade

I have it running two TBI rigs, and I will be helping a friend get one running on his carbed mustang, possibly his VW Bug as well. It's great for conversions because there is no need for baffles, or sumps and it keeps the pump surrounded with fuel no matter the level or motion of the tank.