Guys & Gals, I come to you with my tail between my legs. I read several posts on here, I read the Inject Your Horse series, I collected parts, and I dove in. When I bought my Bronco from Corey, it had and Edelbrock Performer intake w/ Edelbrock carb, an electric external fuel pump, and a host of Accel ignition goodies. However, those higher elevations just made her suck wind.

Before:
http://i40.photobucket.com/albums/e243/ ... kaieb9.jpg
http://i40.photobucket.com/albums/e243/ ... bb9ye1.jpg

I found a Lightning GT40 tubular upper (sold the 351W lower) and an Explorer lower. I bought a lot of parts from an older gentleman that had an EFI swap done on an old Fairlane but removed it in favor of a big ol' roots blower. That lot included a '90 Mustang upper/lower/rail/injectors/egr/tb/mass air/distributor/coil, a Painless wiring harness, an A9L computer, and a MSD 2225 inline pump. Then I bought some -6 AN hoses/fittings/filters. The fuel plan was tank-filter-pump-filter-engine-return. New plug wires and spark plugs while I'm at it. And a K&N cone for the end.

After:
http://i40.photobucket.com/albums/e243/ ... w6d6xs.jpg

At first, that MSD 2225 was stuck. I don't know how it was stored when he removed it. But, since I'd already set up the fuel system, I just replaced it with another MSD 2225. That purrs like a kitten.

Then I realized I didn't have any spark. Following the old cranks-but-doesn't-fire list for 5.0L Mustangs and a volt meter, I was able to determine that the TFI module on the distributor was faulty. Replaced that. BOOM, did I have spark. Got a hell of a backfire on the third try. It cranked, it ran, and it sputtered. It just didn't run well enough for me to back it out of the garage.

After a while, it wouldn't crank. I could hear the starter engage, but the engine just wouldn't turn over. Concern. I got out the breaker bar to turn it over by hand...moved it 2-3 degrees and I could hear fluid. Did I screw up a gasket and get hydrolock? Panic. So pulled all the spark plugs. Sure enough, cylinder 7 is FULL...of something. It wasn't coolant. It looks and smells like gasoline. Cylinder 3 wasn't as tight as when I'd first put it in either. I turn the engine over by hand now and the first compression stroke of cylinder 7 I got plenty more fluid. Again, it's definitely not coolant. I'm still leaning toward fuel. Confused.

Spark plugs for reference (see the moisture around #7):
http://i40.photobucket.com/albums/e243/ ... 0rlalr.jpg
http://i40.photobucket.com/albums/e243/ ... bktn1s.jpg

Any ideas? What have I done? Am I really just a bolt ons guy now that I'm married w/ children? Do I have to ask Santa for a new long block?

Check the injector for that cylinder with a 9V battery. I had one of my junkyard/used injectors flood one of my cylinders because it wouldn't open and close (must've gotten stuck open). Hopefully that's all it is- easy fix.

I agree with Eck. Sounds like a stuck open injector.

Don't forget to change the oil after replacing the injector. Some of that fuel has made its way down to the pan.

Had the opposite on mine. Clogged injector and xcylinder was clean as a whistle. Try rebuilding them or soaking them I. Injector cleaner for a day or two then try to blow them out.

You can pickup a injector rebuild kit online for those, soak them and then use the compressor to blow them out. You can use a 9v battery to open them up in order to blow the crud out of them on the bench.

If it's just one cylinder loading up I'd lean towards a stuck injector too. You might make sure that the injector isn't commanded open all the time though. Simple check with a test light before you pull the rails off.

Alright, the injectors are soaking (I didn't see your idea, EFI Guy, before I had them off).

New issue, there was fuel in the upper manifold. I thought I read somewhere during my install that if the fuel pressure regulator goes South, it could suck fuel right through the vacuum line into the manifold. Any thoughts on that possibility? I did not notice any fuel on any of the other seven spark plugs.

Also, have I hosed this myself? I know in most EFI vehicles, you hear the fuel pump turn on when you turn the key and it sounds like it fills the system and shuts off. I've got my fuel pump on a separate switch. So it could potentially be on for 5-10 seconds before I crank the engine. Am I stuffing too much pressure in there before there's vacuum?

Stats on the fuel pump:
MSD 2225
Free Flow Rate: 43 gph
Maximum Pressure (psi): 40 psi
Notes: Approximate flow is 43 gph (282 lb/hr) gasoline (specific gravity 0.788) @40 psi and 12 volts/5.4 amps.

The pressure regulator could be your problem if it's leaking. I've seen a few do that. But, usually they aren't as bad as you're describing. I suppose it could all be running in the closest cylinder to the vac line.

Having the pump on a toggle isn't going to hurt anything, but it will toss codes. I would for sure have an inertia switch in line though. You don't want a pump that keeps spraying fuel after a nasty accident! When the pump is controlled by the PCM it will shut off when the engine does, it's also a pretty good indicator when your PCM goes bad....https://www.youtube.com/watch?v=-O7FUoQzTB4

yeah, my brother and I each had a regulator go bad. Fuel pours out of the vacuum line when the diaphragm ruptures. Mine ran very rich and was throwing O2 sensor codes.

Alright, soaked all eight injectors for a couple nights. Today, I let them drip dry, sprayed them with some carb cleaner, and hooked them up to a 9V battery. I could hear each one click open and closed. Put all eight back in the truck.

Then I replaced the fuel pressure regulator and put it all back together. I let it turn over a few times without the coil wire connected and without the fuel pump on...hoping to blow out anything that could be left. Followed by an oil and filter change.

Hooked the coil back up, turned on the pump, and she fired right up!!!

Now, a couple idiosyncrasies I've gotta work through:
1. I've still never gotten the truck to fire up via the key. I've got a hi-torque starter with the solenoid on the starter. I've just been turning the key to on and touching the small starter wire to a positive post to turn the starter. Any ideas why it wouldn't fire when I turn the key but will when I turn the key it just cranks and cranks?

2. I've still got a bit of a misfire at low RPMs. It doesn't really like to idle. Idle seems pretty low too. But if I hold it at 2000-2500 RPMs, shes' like butter.

Also...just got her out and drove her around the block.


The got a little bit of popping through the intake under load. I think it's time for a timing light.

You are losing power to your EFI system when the ignition is turned to start. Either you are using the wrong wire to feed power to the EFI, or your ignition switch is bad. Power to the EFI relays needs to come from a terminal on the switch that is hot in run and start.

Popping through the intake is usually because it's running lean. It may have adapted that way because it was trying to compensate for the extra fuel from your regulator. Disconnect the battery for a few minutes and it should reset.

You guys are the best! I've got a 4-day weekend and I'm SO hoping to drive her back to work on Tuesday.

I disconnected the battery after EFI Guy's response a couple days ago. Reconnected today. Double checked my firing order of 13726548 (it's an old block...but must have a late model rotating assembly because that's how the old distributor had it). I got a timing light and set it at 10 degrees (yep, spout disconnected and warmed up). Drove her around the block and I still felt a lot of the same symptoms. Intake pops under load at low RPMs. Smooth over 2K RPMs.

I then came back to my garage and set the timing to 12 degrees. Around the block and same symptoms.

I took some videos. For the in cab shot, I opened the lift gate so you can hear everything:
https://youtu.be/mlaAtqTH0MY

Then here's under the hood. The pops are not as obvious:
https://youtu.be/fwW23HJy7Wk

Here's the exhaust at idle. Sounds a bit more lopey than it was with the carb:
https://youtu.be/UHKmq8C5P0M

That should have an early firing order cam in it unless you changed it from the one that was in it. And it's 28oz imbalance. So all early stuff. 15426378 should be the firing order.


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Unless it has a 351w cam in it, but as far as I knew it was early 302. It's been a while since I worked on it


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Sounds like it's only popping when you stab the throttle... Or does it do it driving down the road when you ease into it a little slower?

Is that throttle body factory sized or is it a bigger, aftermarket unit?

Geez. I'm in deep. If I had a 15426378 firing order and I wired it to 13726548, would it exhibit these symptoms? Or what would it do?

Before I started the project, I'd swear I checked and it had an HO firing order. But now when I go back through pictures, it does look like the non-HO firing order.

Specifically this picture where you can see that 2 is fourth, 3 is sixth, and 4 is third...
http://i40.photobucket.com/albums/e243/ ... rml1ht.png

So, this morning, I changed the plug wires to the non-HO firing order, disconnected the negative for a few minutes, and tried to start her up. It just cranked. Not even a fire. I then put the plug wires back to the HO firing order, disconnected the negative for a few minutes, and she fired right up. Of course, still exhibiting the older symptoms of backfiring through the intake at low RPM revs.

I just got off the phone with Corey and he's given me a couple of leads.

EFI Guy,
It is an OEM TB. But it's the one that came with my Lightning stuff (65mm) not the Mustang stuff (60mm). I didn't pick them for size. But the Mustang parts were rather dirty. And it does still pop a bit when I ease onto it. I didn't drive too far. But while taking a turn in second, I'll give it a little gas and hear a POP...POP...POP until I ease back off. Say I went uphill in third, it would still POP...POP...POP until I downshift into second and got some higher RPMs...then it would be fairly smooth.

The two firing orders are not different enough to cause it not to fire if the wrong one is used. There are only 4 numbers swapped.

Man, I had that thing all sorts of messed up. This morning, I had some time to back up, go make a plan with all the crap that's been going through my head, and redo some things. I also talked the wife into helping me for a bit.

After pulling a valve cover, I was able to confirm it was the non-HO firing order.

I got it back to TDC, ran the plug wires in the CORRECT pattern, and switched the wiring for the injectors for 5-3 and 4-7. Hooked the battery back up and it started on the first try. After warming it up, I disconnected the spout and set the timing at 10 degrees.

Done (well, done enough to drive...I've got a list of things to button up later)
https://youtu.be/lcch3RZPp-k

Thank you all for your help and patience! I can't wait to show her off! Now it's time for some interior spruce ups.

Congratulations Great. News!! Gives me hope for my EFI conversion.

I've been driving the truck to work the last couple weeks. It does OK. The idle is still a little cyclical when it's cold. I feel like the low end (mostly noticeable in 3rd and 4th) is lacking some power. Here are the codes I'm getting with key-on-engine-off:

031 - EGR Valve Position/Pressure Feedback EGR Circuit Below Minimum Voltage
067 - Clutch Switch Circuit Failure
081 - Secondary Air Diverter Circuit Failure
082 - Secondary Air Bypass Circuit Failure
085 - CANP Circuit Failure
084 - EGR Valve Position/Pressure Feedback EGR/EGR Control Circuit Failure
095 - Fuel Pump Circuit Open-PCM To Motor Ground

What do you guys think?

I'm not running EGR. The EGR spacer is in and the back has a plate closing it off. And the plug from the wiring harness is just hanging out.

I should also point out that I have an exhaust leak(s) somewhere. It's just been too darn cold for me to want to crawl around and find it. The fox body I drove in HS/college had cutouts and it definitely reminds me of that open exhaust sound. So, if any of these you think are related to backpressure issues, I've got 'em.