OK, Here's what i'm dealing with... 91 silver anniversary Bronco, 5.0 bored .040 over, flattop pistons, Crane cam,from my wrecked 89 bronco. Trans was changed from the E4OD to a M5OD,wiring and all, Tcase was swapped from e-shift to manual shift. Driveshaft was modified to fit using the yoke from 89 case and yoke from 89 8.8 axle. This much works OK except for the engine is not building the horses it should. Have to be going downhill to get over 60mph.
Error codes are 52,(power steering?) and 34 (egr malfunction?) egr is not very old and have replaced position sensor twice in last year when it was in 89. Continuous code that comes up is 95. Replace low pressure pump? What is a good way to test/diagnose this? Any help for my egr woes? tnx ahead.

 

How's the fuel pressure?

Any restrictions in the air flow?

Tire size, axle ratio? do you have a tach?

 

Codes are codes... The answers are in them. First, which test gave you Code 52? KOEO or KOER? If it came up in the KOER test, the steering was not cycled lock to lock during the test as required. Repeat the KOER test and cycle the steering at least 1.5 turns each direction immediately AFTER the ID code is displayed.

Code 34 indicates that the voltage returned from the EVP sensor is higher than it should have been during the KOER test. This means one of two things. Either the EGR valve is not seating completely and thus not functioning properly (needs a good cleaning) OR the EVP sensor wiring or the sensor itself is the culprit. This is the only meaning for Code 34 with a vehicle equipped with an EVP sensor like your truck.

Code 95 in continuous memory codes indicates a potential issue with either the ICM or the inertia switch in most cases. To "wiggle" test is your best course of action. With the engine running, tap on the ICM and wiggle the connector and wiring harness running to it. If the engine stumbles or dies, repair or replace the entire pigtail in the wiring harness to the ICM. Replacement of the ICM could be necessary as well.

 

ICM? Not exactly sure what/where that is. Codes are all KOEO. I'll do some more tests when I get it in the garage again,have couple of deer hanging there.

 

Ok, since we are dealing with KOEO Codes only, ignore Code 52 for right now.

ICM = (Integrated Control Module) is mounted on the distributor casting below the cap in your 91. The ICM is connected to the main wiring harness via a seven-pin connector at one end of the module. The "wiggle test" will tell you if the connection, or the ICM itself are causing intermittent spark timing issues which would of course keep the engine from performing as expected.

 

OK, I changed that less then a year ago because I lost spark during a blizzard. That's not good timing. HA lol

 

The unfortunate thing about the location (on the distributor casting) of the ICM on pre-1992 models is that engine temperatures tend to wreak havoc on them... which is why they got moved to the passenger side inner fender and set in a huge heat sink in 1992.

 

Updating this for anyone following it,fuel pump quit working altogether now. Checked relay etc. Pump won't run by shorting the fuel pump terminal to ground either. Time to drop the tank and change the pump, '91 seems to be first year for the FDM style pump, as there's only the one in the tank and none on the frame.

 

Yep, prior to 91 there was a low-pressure unit in the tank and a high pressure unit on the frame rail.

 

1990 Bronco has one Fuel pump in tank.

 

I hope my exploper holds together til I get the bugs out of my 91, it's bugging me to have a cool ride that I can't drive!!

 

And one on the frame rail unless the one in the tank has been replaced with the newer high pressure version used on the 91 and newer trucks.

 

Quoting further from the 1990 Truck Shop Manual, that I have in my posession at the current time and place, "The electric fuel delivery system used on the F-Series/Bronco Electronic Fuel Injection (EFI) engines consists of a modular, in-tank reservoir (ITR) assembly. The ITR unit includes a high pressure fuel pump, venturie jet pump, supply check valve, and a shuttle selector valve all located internally to an in-tank reservoir assembly mounted from the fuel tank sender flange" Page 24-50-1 Fuel Tanks and Lines and Fuel Evaporative Emissions Control system.

Section 24-36 Fuel Pump-electric (ITR) goes into even more descriptive language that describes the intank high pressure fuel pump.

And the 1990 Bronco out in the driveway had the original Ford Fuel Pump, pictures of it can be seen in my gallery if it was working, and the Original Ford Fuel Pump was replaced with a Ford new part so I know that in 1990 Ford had the one fuel pump system in the Bronco and in the F-Series Trucks.

 

Not that it matters, but mine is also single pump as a 1990.

 

Has anyone here ordered parts from rockautoparts.com before? Found a fuel pump there is exacly the same as in local parts store, brand and part# same... $40 cheaper! I have used them before to buy new headlight bucket and tailight assy for my '89 bronc. Went with a Performace Electronics pump for $43.79 + shipping.