84 T-Type wont go

edfiero1

Member
I've had a series of problem with my car which all seem unrelated but I'm ready to roll this car off a cliff.
First car won't start. No fuel pressure in the rail. Change out Fuel Pump. Works better but still have problems starting. Then find problem with prior owners Hotwire of the FP.
Fix that, then the car starts, but immediately dies. Suspect MAF, because the car will run with the MAF unplugged. Buy LT1 MAF and Translator.
Car starts up and idles great now.
Go for a test drive, as soon as the car gets under load like going up a hill, it falls on its face. Engine shutters, backfires slightly and wont Rev over 3000.
I tried the translator in both the default (extended) setting and the 'other' setting. It made no difference.

Attached is real quick data log trying to come up my driveway. You can see Throttle position increase and RPM starts to increase, then RPM actually goes down. WTH?

Any ideas? Car was running fine until a couple of weeks ago when I had the no start problem.
tried posting the log as CSV and XLS but the forum doesn't appear to like those formats.
 

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TexasT

Texas, Where are you from
I'd make a reading on the coil leads on each coil with a meter on ohms. They should have a reading(don't remember off the top of my head) and be fairly equal on each of the three. What about the plugs and wires? how old? Gap?

These cars can be very frustrating. Keep at it.

I unloaded the log and as the tps is going up, and as you pointed out the rpm is going down so is the O2. This shouts to me that you still have a fuel problem. Maybe fpr, delivery, or something. What do you have for a base pressure? and does it stay there while driving? The frames around #357 show the O2 real low. What pump are you using? Does it have a full 12 or more V at the connector new the rear bumper? What does your pump hanger look like? corrosion is electricity"s cryptonite.
 
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TexasT

Texas, Where are you from
I guess i'm assuming you have a meter of some sort. and know how to operate it. if not here is a "less" expensive one and a book on how to.
https://www.ebay.com/itm/Digital-Vo...155775?hash=item41d7f6e37f:g:jtoAAOSwIJlaTYxT
s-l1600voltmeter.jpg
https://www.ebay.com/itm/B0006F1DL4...901611?hash=item4672cf572b:g:PV8AAOSwPAxaPCri
s-l400meter book.jpg
 

edfiero1

Member
Well it's a STILL a fuel problem. I put the fuel pressure guage on it and when the engine is bogging down the pressure is dropping down to 20.

The pump is a DW200 only about a month old.

How do I determine if this is a problem with the pump or maybe the fuel pressure regulator. The regulator is a stock non adjustable style of unknown age.
 

ScottHeidinger

Active Member
My car had a half ass hot wire with a cheap ass relay when I bought it. Best to buy a quality hot wire kit with a quality relay once. Also check your ground wires for the fuel pump. If you’re using the stock fuel pump wiring inside the tank the sending unit you probably should consider upgrading that to. Turbo charged cars and not enough fuel is a very expensive combination. I would also use a DW 300 not the 200.


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TexasT

Texas, Where are you from
I have a dw200 in my car. Works fine. It is an 84 hotair, that pump moves plenty of fuel. But not if it doesn't have voltage.
You can make your own hot wire or buy a kit. Just need some wire and a decent relay.

I would think if the regulator is original, it isn't up to the task. corn in the fuel is hard on rubber and that rubber wasn't even put in thinking about the corrosive nature of the e10. Do you have a different fpr to try out?
 

edfiero1

Member
The Saga Continues

So here is the latest update. I've done the following:
1. Replaced the Fuel Pressure Regulator
2. Replaced the Fuel filter. (Old one didn't seem to be bad - could blow thru it with no restriction)
3. Ran a new temporary hot wire from the battery directly to the pump. No relay.

And here is the crazy behavior

At idle fuel pressure is about 32 with the vacuum connected. I confirmed that if Pinch the return it goes to 90+
While driving at light throttle fuel pressure increases to around 40. However if I give it more than about 30% throttle, the fuel pressure actually decreases to the point of the engine starving for fuel. If I let off the gas, pressure returns to around 30, then I can continue on with light throttle.

I'm stumped. Is my new regulator bad? Can the fuel pump still be bad, even though it gave 90+lbs with the line pinched? What else should I check to identify the cause?
 

ScottHeidinger

Active Member
As mentioned above the vacuum source for the FPR could be a issue if there is a check valve in the wrong place. Other possibilities include a solid ground wire for the fuel pump. Verify the ground connection from the pump connection to the frame. I assume the hot wire didn’t go all the way to the pump so your issue is most likely in the wiring that is left from your Hotwire to the actual pump. The wiring harness that goes from the rear of the car thru the top of the gas tank could have issues.


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ScottHeidinger

Active Member
Do you have a scan master? The only other reason I could think of is if your alternator is not producing enough for the pump under load. I would think you would notice other electrical issues if that was the issue. Dim head lights, hvac blower slowing or other issues.


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Jerryl

Tall Chinese Guy
Pump specs.
255 lph is sufficient for 55 lb injectors @85% DC on 93 pump.
 

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edfiero1

Member
As mentioned above the vacuum source for the FPR could be a issue if there is a check valve in the wrong place. Other possibilities include a solid ground wire for the fuel pump. Verify the ground connection from the pump connection to the frame. I assume the hot wire didn’t go all the way to the pump so your issue is most likely in the wiring that is left from your Hotwire to the actual pump. The wiring harness that goes from the rear of the car thru the top of the gas tank could have issues.


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Thanks Scott. I'm also running a ground direct from the battery back to the pump. Hot wire is direct.
Regarding vacuum..... I wouldn't rule out that I have a bad check valve 'SOMEWHERE', but if my line goes directly from the Vacuum Block to the FPR, does a bad check valve some where else in the system even matter??
FWIW, car is an 84 Hot Air converted to an 87 ECM.
 

ScottHeidinger

Active Member
As long as the check valve isn’t in line with the vacuum line going to the FPR you should be fine. It’s probably time to drop the tank and inspect the wiring and the hose connections like the other guys said. I will bet you will find your issue once you pull the pump back out of the tank. If you’re not sure post some pics of the pump and sending unit when you get it out and one of us will probably be able to see what’s wrong. The DW200 should be enough fuel for a stock or mild build on 93 octane. I know we all hate to have to drop the tank but I think your problem will be found there.


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TexasT

Texas, Where are you from
All the power to the stock pump goes through this little set of pins. If they are corroded it doesn't work well.
Also the hose used to go from the pump to the hanger must be suitable for submersion. The fuel can eat the outside right off the hose. And it needs to be well secured. Good hose clamps and securing the pump to the hanger is important so it doesn't come loose.

Dropping the tank is only so much fun. Make sure the lines from the tank to the hard lines are in good condition. If they are original now might be a good time for replacement.
Get the car up on stands and I use a floor jack and a bunch of wood blocks to secure the tank so it doesn't fall off the jack.
 

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