Fuel injection questions

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Wrencher

Wrencher

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Hello all,

One of my neighbors has offered to sell me an 88 1/2 ton truck with a 318 tbi/auto trans for a mere $400. I'm going to go get it this week. From a looks perspective, it's a lot nicer than the price suggests. All the paint is there and the interior isn't ratted out. That's the white meat, now on the the red meat lol.

They put a 318 engine in this truck to replace the original one that had blown. That engine came out of the same year van, according to the owners. In 6 months of tinkering, they have yet to get it running. Him and his son are completely clueless on fuel injection and have wasted a lot of time with it. The engine is getting so much fuel that it is filling the oil pan with raw fuel. They have replaced both the injectors in the throttle body with auto zone units and still have the same problem.

I can't begin to tell you what it even looks like under the hood but they said all the connectors are plugged in where they need to go. For the price, I can probably scrap it for 80% of my investment and CLEAR the engine and tranny so I'm not worried much about it.

Here is my thought process;
Fix the truck and flip it, or possibly pull the motor and trans and put it in my '66. I can still make the truck run again with the slant six, so I'd have a running truck either way.

The thought of having fuel injection in my '66 is killing me. Especially since the ECM, wiring, and everything I probably need are going to be in the truck already. However, I need to fix it in the truck before making that decision. Any ideas? To me this screams grounding issue, but I'm no expert on this stuff.

I can always get a small block intake and put a carburetor on it if I want, but I'd rather see if I can fix it right. Let me know.
 
........................random thoughts...........................

1---If these guys have hacked up the wiring, or burned things up, you could be inheriting someone elses troubles that would be nearly endless, might be easier IF you intend to use this stuff, to pull out the relevant parts of the harness and components and wire it up so you KNOW it will work to get it fired. Of course this might not bode well for "flipping" the rest of the truck. AND if the engines were "same year," it should have been easy................hook up the connectors as they came out, etc.

2--If they've filled the pan with gas, as you say, this engine might need rings at the least

3--Mopar ECU's are not known for being "reprogrammable friendly." Somethng that old probably doesn't have the security interlock problems, but...........

4--Just how comfortable are you with electrics, and can you get documentation on the system? People keep "telling" me that "it's out there" but when push comes to shove, actually FINDING diagrams and documentation seems to be elusive.
 
1 - these guys are not very sure of what they are doing. Merely parts changers at best. My thought process is as of right now to make sure everything is as they say it is, see if they have hacked up the original harness, and have a look at it taking nothing for granted. I've seen the truck running and driving so I am sure that they created the problem with the engine swap.

2- I agree. Not knowing how long before they drained the fuel is scary. However a set of rings & bearings are cheap, and I plan on going through it with gaskets and an oil pump before i put it in the Dart. But that is why I really want to hear it run before I pull it from the truck, even if I swap it to a carb. I can diagnose what it needs that way. Compression test, thrust movement, timing chain, etc.

3- are you suggesting that they might have tried to tinker with the programming? I wouldn't think so because they don't have a clue as to what all the sensors even are, much less be able to plug a laptop into it

4- I'm one of the guys that rather enjoys the electrical side. I have no problems digging in and running with it. However, as of right now I don't have any documentation and will work on getting a shop manual. Admittedly, I'm more comfortable working on the new stuff as they are just easier.
 
To get that much gas in the engine might indicate a plumbing problem, like fuel line hooked to a vacuum port. It could also be from a shorted injector driver, resulting in them being full on when the key is on. In either case the engine likely could not run at all.

If working correctly there should be TBI injector pulses that range from less than 1mS to several mS depending on operating conditions.

As others suggest, armed with manuals and such, completely leave no stones untouched. I have done this with many orphaned cars, much is learned in the process.
 
My comment about the original computer is referring to whatever might need to be done to get it to run (at all) or correctly with your specific build / swap. I've seen posts, though that evidently there are people that "do this" if needed.

Even Ferd computers seem to have a better track record so far as swaps and DIY than Mopar.

For example, over at "Binder Planet" many guys are reburning their own homemade GM chips to swap GM stuff into their CorNationalInterBinders. I don't think there's any of that going on with the Mopar computers.

I'm running currently a Holley Commander 950 TBI, and made the decision to upgrade to their latest HP computer. But I've considered going with Megasquirt, which is pretty much all DIY
 
I agree with 67Dart273, the 88 vintage EFI may not be a great system to start with. I have experience with similar 88 2.2L TBI, it worked, but was far from optimal. Mopar spent too much time on the earlier solenoid controlled metering rod carbs. They were a flop, and then they hurried into EFI. The systems are not well documented, and very few if any are doing work with ECUs.

I have a new old stock 2B TBI that I plan to use on my 66 Barracuda, but I will do the ECU. If that works, I might pull the TBI injectors and go multi-port injectors and use TBI only as TB. Time will tell if I am able to complete a couple projects and get on with that.
 
Seems like a 2bbl will ensure a running engine again. I wasn't aware of mopars were so bad in the early years of F.I.
 
Wrencher said:
Seems like a 2bbl will ensure a running engine again. I wasn't aware of mopars were so bad in the early years of F.I.
Click to expand...


they weren't too bad at all if you know how to work on them. I sell kits that use the 1988-1991 dodge TBI components as well as wiring, I'm sure if you buy it I can walk you through the wiring
 
Well I completely understand the idea and operation of efi, however, THESE particular setups, their quirks and most common issues and failure points. I am completely willing to learn if it is worth the effort. I'd really like the idea of a more modern efi in an old car like this. At a $400 buy in, and the opportunity to fix it before it makes its way into my car, I think it's worth the effort.

Thanks for the links. I'm going to go learn something :)
 
If you have any questions, don't be afraid to log in and post up over on the BP.
I don't care what engine the TBI is bolted to and the ECM doesn't care either.

Tuning is a very important part of an EFI conversion along with parts availability.

I hate chevys but chose to use the GM EFI due to the completely hacked program for "free" tuning software and the parts are cheap and every where.
You can bolt any EFI system on any engine just like bolting a on a carb right out of the boz from summit. But that doesn't mean it's tuned.
Then you install your new cam and headers...you need to be able to tune it again.
Get a system that is going to do what you need it to do, not just something that is convenient. I started by using all junkyard parts for the GM TBI for about $300.
But over the years my time is worth more than some of my money so some things I just pay for and now I build complete systems for others who just don't have the time to build a system.

Pick the right system and you will be happy. Pick the wrong one and you will be bolting the junk carb back on.
 
Wrencher said:
Hello all,
I can't begin to tell you what it even looks like under the hood but they said all the connectors are plugged in where they need to go.
Click to expand...

With respects Esteemed Posters,

Given the above baseline info I think the BASIC mechanical needs to be verified before the Electronics are 'called on the carpet '.

? fuel pressure regulator ? seems there were a few (lol) updates.

pinched return line ? not the first time 'many hands have spoiled the broth '

just My humble $.02
 
well, time for a six month update...... lol.

My brother bought the truck, and wants to use it as a hauler. He bought his first home, and really needs a truck to make Home Depot runs. We have let the truck just sit there since he bought it, but his motivation has returned and Im glad to help. I got the truck pulled up to my driveway, and it looks like amateur hour under the hood. Vacuum lines hanging all over the place, connectors unplugged, harnesses cut off, the whole nine yards.

I told him to forget it and buy himself a 4bbl intake, and I would give him an edelbrock 1405 I had gotten in a trade a while back. I went outside today and pulled the intake and valve covers off. I'm going to get the 4bbl intake on it this weekend. The engine looks sound, at least under the intake. I was happy to see no oil buildup or cam wear.

As I was cleaning up for the day pondering stuff in my head, one question did pop into my head that I have never really sorted out. I am hoping that you can point me in the right direction.

Fuel pressure -I am going from a TBI to a carb, and unless I am mistaking, the fuel pressure will be a little too high for the carb float to keep under control. About 6 pounds higher than needed. I thought about bolting in a mechanical fuel pump from a carbureted engine, but I would still have to stop the electric fuel pump (which Im assuming is in the tank) from pushing fuel. Then I would still have a return line to deal with.
 
Wrencher said:
well, time for a six month update...... lol.

My brother bought the truck, and wants to use it as a hauler. He bought his first home, and really needs a truck to make Home Depot runs. We have let the truck just sit there since he bought it, but his motivation has returned and Im glad to help. I got the truck pulled up to my driveway, and it looks like amateur hour under the hood. Vacuum lines hanging all over the place, connectors unplugged, harnesses cut off, the whole nine yards.

I told him to forget it and buy himself a 4bbl intake, and I would give him an edelbrock 1405 I had gotten in a trade a while back. I went outside today and pulled the intake and valve covers off. I'm going to get the 4bbl intake on it this weekend. The engine looks sound, at least under the intake. I was happy to see no oil buildup or cam wear.

As I was cleaning up for the day pondering stuff in my head, one question did pop into my head that I have never really sorted out. I am hoping that you can point me in the right direction.

Fuel pressure -I am going from a TBI to a carb, and unless I am mistaking, the fuel pressure will be a little too high for the carb float to keep under control. About 6 pounds higher than needed. I thought about bolting in a mechanical fuel pump from a carbureted engine, but I would still have to stop the electric fuel pump (which Im assuming is in the tank) from pushing fuel. Then I would still have a return line to deal with.
Click to expand...


just put in a bypass style regulator if your keen on getting rid of the fuel injection

but with a wiring diagram and a days work most anyone can get TBI functioning, theres not much to it
 
TBI fuel pressure is about 12-14psi. If you can, you could run a holley blue/black regulator and dial in 7 psi holley or 5 psi Edelbrock. If you got all the electronics, slough them off to a brave soul on the sale board. I bet more than 1 person would be interested in the entire TBI setup even if it had a hacked harness (like me!) You can megasquirt even a TBI, but the ECU should be more than willing to run a stock 273/318 as it can adjust duty cycle to meet engine demand as long as the O2 sensors are hooked up. Now I dont know what it uses for crank sensor or cam sensor but it shouldnt be too hard to figure out. Even an MS1 can do it (dont know about Mopar idle control on an MS1 though, but you can put an external jeep idle control valve on it and run it like a Ford in PWM mode) and the MS1 are pretty cheap, either to buy or make. The schematic and source codes are out there, about $30 in parts, and itll do ignition too.
 
I'll certainly keep the parts together. The P.O. actually spent $100 on new auto zone injectors. So if you wanted to take the time and sort out the harness hacks, it might prove to be a worthwhile venture. I'll be thrilled just to get the thing up and running, even if its '60's style. As a parts runner/backup vehicle, the carb will be just fine IMHO.
 
I just read most of the posts again. My thinking is if the MAP sensor is bad, or vacuum line not connected to the intake, the mixture goes full rich. It is possible to test the MAP sensor, just 3 wires. It has 5V power, output and ground. You can use a meter and mity-vac to test. With key on, using meter on, verify that the sensor has 5V and ground, the other terminal will vary from a few tenths at high vacuum to near 5V with no vacuum.

If the engine coolant sensor is open or unconnected, the fuel will go rich, thinking it is sub zero.

There is a key on off sequence to read fail codes via blinking MIL dash light. Switch key on, off, on, off, on keep on. MIL will blink, count blinks that occur, longer pause separates codes. They end in 55. I think Allpar and othe places list codes, they are fairly standard for 80's Mopars.
 
TBI is easier to diagnose than MPFI since you can see the fuel spraying above the throttle plates. If your controller is like my Holley Pro-jection 2D, the injectors should spray in synch with the engine rpm. Holley uses the coil- signal, relying on the engine's ignition system to sense the crank. The factory Mopar system probably uses the raw crank signal instead. Regardless, that makes fuel pulsing linear with rpm, which is needed. Pro-jection then varies the spray "pulse width" with throttle position (TPS). The factory system probably uses manifold pressure (MAP) and temperature (IAT) instead, which is better. Pro-jection has 3 knobs for the user to "warp" the TPS effect with rpm. The factory probably uses a digital map for that. I agree that if it sprays continuously, the injector control wire is probably grounded (or transistor failed short). Just like an ignition coil, constant +12 V is applied to one side of the injector coil and the control transistor connects the other side to ground to turn on the coil. Many more details on the megasquirt site.

Worst-case, you could substitute another fuel controller just to get it driving. Holley's Commander 950 would be best. I bought an ECU alone for $150 off ebay. Easier and cheaper would be a Pro-jection box. I bought a spare one for $15 off ebay. The earliest "by MSD" boxes are easiest to wire since they use weather-pack connectors. Those are also more robust. The wimpy connector Holley put on later boxes is problematic (wires pull out). Megasquirt is an option, but more work and they aren't cheap (<$200), but there is excellent info and support. A GM box is another option. Check out Bill USN-1's Binder Planet site. Howell Engineering customizes GM boxes. One to avoid is MSD's early EFI box. They quickly fried the COM port, so MSD dropped it after 2 years and left customers hanging. It was an early version of Meany's BigStuff1 box, but nobody fixes them. Meany makes BigStuff3 EFI now for hard-core racers.
 
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