1990 Bronco XLT 5.8l

[King Daddy Rabbit]

Not sure where you live. Here in Texas my 1990 is considered an antique because it’s more than 25 years old. Under state law no emissions equipment whatsoever is required. I bought it new in November 1989. I have always loved by Bronco, but was frustrated with the mess under the hood and the lack of power. This last year, I sat down and looked at all my options. What I have done is take the 302 out and stroked it to 331. All original omissions devices are gone. Also, all the fuel injection. I replaced them with an Edelbrock Pro Flo 4 system. All that was required is O2 sensor. Unit is self tuning had a few wiring issues, but nothing major. Transmission kick down lever had to be addressed. Also had to change fuel pump to the unit with higher pressure. I am in love with my Bronco again like the day I bought it 32 yrs ago. It now has 408 hp. All the goofy giant intake, vapor canisters, air pumps, converters, pipes blocking spark plugs, etc, etc GONE. Hallelujah! Just a nice looking aluminum intake topped with throttle body. No monstrous air intake tubes and square filters in cheap plastic boxes. Unit is tuned through Bluetooth with laptop or optional tablet that comes with it. I got it where I like it and have had zero issues. Ability there to adjust all sorts of things from race to mild. Not into all that. Looked into Holley setup but more problems reported and geared more towards racers. Mileage is up as high as 20 mph if foot kept in check. Power is fantastic. Cam selected to get max power 1500-6000 rpm so pump gas works fine. The biggest issue I ran into was finding full length headers I liked. Shortys from Edelbrock were installed in early 2000s to replace cracked manifold. Good alternative to another OEM manifold but still in the way and not very functional or cool. Wound up having a custom set made. $1300. Ouch. But now they are doing a headers job correctly and tone is perfect. We went to eat at favorite place a few weeks ago. There was small car show in parking lot. After we finished and were leaving several people approached and wanted to hear Bronco story. Wound up convincing us to back in with them and open hood. Was getting more oohs and ahhs and questions then guys with gorgeous 1500 hp twin turbo street cars, T buckets, low riders. Crazy. Under hood is nothing like those. Clean. Enough chrome and color to be tasteful. But sure not my idea of show car. But evidently a lot of folks have wanted to do cleanups on their older vehicles and were thrilled to find out they could. At least in Texas. Anyway it’s a blast to drive again. And I’m amazed at the interest in Broncos, Blazers, even old awful Dodge Ramchargers by people from high school to over 60 like me.
This does not answer your question at all. Just an option to clean up a mess from the past to your liking on your clean sheet of paper.

 

[Motech]

When did OBDI come in?

It's a little tricky because OBD I was never a thing until OBD II was a thing.

But to answer your OBD II was globally mandated for all manufacturers passenger cars starting in 1996, with the option to delay their light duty truck certifications until 1998 for retooling burdens.

Was it only "the counting the flashes system"? (nothing B4 or after that?

That was how We The People could access codes on many early systems. Many foreign and import lines were flash-only long after GM and Chrysler were providing data and bidirectional command in the early eighties. All manufacturers eventually caught up by the late eighties, with Ford holding out 'til early nineties.

So no, flashing codes has always been evolving. But equipment to access factory data was expensive. Plus every make had a different system, with constant changes causing big learning curves, especially independent shops that worked on many makes. Heck, even finding the diagnostic connectors was sometimes a challenge. Dealership techs had it easy man.

About that time, the late eighties, the California Air Resource Board (CARB) had become a little drunk with all the influence bestowed upon them by Bostonians, leftern strongarms and tree huggers the world over and began to seriously flex their joy-banning Nanny muscles beyond the confines of the Golden State. They got busy convincing the world that all manufacturers' needed to standardize their On Board Diagnostic software to a universal, one size fits all so we independents and savvy motorists would have access to universal criteria with the same OS and code enabling triggers, with orders to illuminate the Check Engine Light when any glitch is detected that could increase emissions by 50%.

And by god, it worked. They got their way with the entire globe!

So who do they partner up with to develop this gargantuan gloal takeover and genetic mutilation of the motor worlds proprietary foundation?

Yup, Ford.

Ford's EEC IV was the last to release data because their OS was (and is) the most efficient, durable and reliable with their On Demand self test diagnostic technology and automated repair confirmation that technicians who understood Ford's tech didn't need to run confirmation tests. Ya, Ford had it nailed, and CARB called on them to basically modify their superior programming to meet the lofty OBD II purpose and results that the entire globe was forced to accept.

It's also why the entire globe got a two-year reprieve on their light truck compliance too. Ford was still running 35 year Windsor designs because they were too busy schlepping around with CARB to retool for production of the Triton rollout. That and a little empathy for the even bigger headache of pulling diesels into the OBD II party.

Easy peasy, no? Good god no.

And then there's the most diabolical emissions control mandate you've never heard of:

The bloody >~~OBD III~~<
​

TO BE CONTINUED...???

​

---

---

 

[racrx]

so i bought a fuel pressure tester from harbor frieght. i tested my fuel pressure and it was where it should be. koeo and koer so much for the rental at the auto parts store. i do notice when i shut off the key the pressure quickly drops to about 20 and stays there for a bit. im gonna siphon out the old gas and see if it helps. like i said earlier starts and idles but when i try to drive it it barely makes 20mph? and runs really rough like it missing. also gonna pinch of the return line to see if it holds pressure. any other ideas? really want to get this road worthy soon. also checked number 1 plug and it looks lean. ANY HELP WOULD BE REALLY APPRECIATED

 

[Motech]

ANY HELP WOULD BE REALLY APPRECIATED

Drive it with your new gauge attached and taped to your windshield.

• If pressure drops when you accelerate, there it is, and you will likely need a new pump and filter.
• If it stays rock-steady over 40 psi when accelerating, look elsewhere.

 

[Unthrottled]

Yo racrx,
See Table 12 below on Left Side;
View attachment 30667
Ignore Scope Engine for now to save your $
Quick Test is the Diagnostic Trouble Code Test
Check Fuel Pressure & IAC port in throttle body.for gunk.
View attachment 193621
●See my Vacuum leak test in post #11 includes jowens1126 HVAC Control Panel info @ Help with dtc codes and idle

Hey @miesk5

I'd like to get myself a copy of the repair manual you reference here with your reply on this thread, showing Table 12 and Table 14. These are awesome tables, really helpful.

Can you please let me know the name of the manual and whether they are still available for purchase?

Thanks!

 

[miesk5]

Yo Unthrottlrd,
Here they are. May have some duplicates

 

[Unthrottled]

Yo Unthrottlrd,
Here they are. May have some duplicates

@miesk5

Thanks a million!

 

[goodO1boydws]

so i bought a fuel pressure tester from harbor frieght. i tested my fuel pressure and it was where it should be. koeo and koer so much for the rental at the auto parts store. i do notice when i shut off the key the pressure quickly drops to about 20 and stays there for a bit. im gonna siphon out the old gas and see if it helps. like i said earlier starts and idles but when i try to drive it it barely makes 20mph? and runs really rough like it missing. also gonna pinch of the return line to see if it holds pressure. any other ideas? really want to get this road worthy soon. also checked number 1 plug and it looks lean. ANY HELP WOULD BE REALLY APPRECIATED

Have you done a compression and cylinder leak down test yet?

You may have a couple sticky valves or valve/valve seat matings that aren't sealing properly.

The engine COULD still be able to start and keep running fairly smoothly on as few as 4-5 decently sealing cylinders, with a couple marginal ones and 1 or 2 poorly sealing ones-AT IDLE as idling requires very little power.........

 

[Unthrottled]

Hi @miesk5

I just noticed your Big Bronco Repair site, BroncoLinks.com, and checked it out. Wow, what a find! A wealth of resources and great information. I wish I had stumbled across it years ago. I just saved it to my favorites. Can't wait to put it to use.

Can you please let me know which repair manual your attachments from earlier in this thread came from? I'd really like to purchase a copy of the manual for my garage?

What it Chiltons? Hayes? Another manual?

Please let me know.

Thank you!

Unthrottled

 

[racrx]

so now i put in new tank, fuel pump and sending unit. also the right remanufactured computer. got it all done and it doesnt start. cranks but no start. even with the really old gas and the wrong remanufactured computer it ran great at idle just bad under load. now it cranks but wont run. no fuel pressure at the rail. pump run with key turned on for a second or two. also jumped the fuel pump it runs but no pressure. any ideas are welcome. im at the end of my rope. checked for leaks none. dont know what else to do. HELP. thank you for any replies

 

[L\Bronco]

so now i put in new tank, fuel pump and sending unit. also the right remanufactured computer. got it all done and it doesnt start. cranks but no start. even with the really old gas and the wrong remanufactured computer it ran great at idle just bad under load. now it cranks but wont run. no fuel pressure at the rail. pump run with key turned on for a second or two. also jumped the fuel pump it runs but no pressure. any ideas are welcome. im at the end of my rope. checked for leaks none. dont know what else to do. HELP. thank you for any replies

Im a bit late to the party here, but it appears that it used to have good fuel pressure with the old pump and tank and now has none?
If that is the case, I would say you either got a bad pump out of the box, (No impeller or leaking at the hose that connects the pump to the steel line inside the tank.)
Or, the tank and sender are mis matched. They used to make an extended range tank for big broncos, I believe it was 22 and 33 gal capacity. Not 100% sure it was available for your year, but, if you got a 33 gal tank and a 22 gal sender, the pickup will be 3-4" off of the bottom. How much gas did you put in it?
Hope that helps
Cheers

 

[racrx]

i put in 11 gallons. its a 33 gal tank. got the pump from bronco grave yard. i can here it run and jump the test connector and make it run but no pressure. any change a regulator could cause this. but again ran before had pressure but would go to 10 lbs when the key was turned off????? i hope its not the pump. its not a fun job

 

[L\Bronco]

i put in 11 gallons. its a 33 gal tank. got the pump from bronco grave yard. i can here it run and jump the test connector and make it run but no pressure. any change a regulator could cause this. but again ran before had pressure but would go to 10 lbs when the key was turned off????? i hope its not the pump. its not a fun job

The leakdown spec from ford is 10 psi in 30 seconds. If yours drops to 10 and holds for a while its good enough to drive on.
Its unlikely its the pressure regulator as it would have to stick wide open. Ive never seen one do that.
Does your pressure gauge have a bleed hose and valve?
If so, put the hose in a container, open the bleed valve and jump the connector, you should get half a quart in 30 seconds max. if thats good The pump is working.
Good luck
Cheers

 

[miesk5]

Hey @miesk5

I'd like to get myself a copy of the repair manual you reference here with your reply on this thread, showing Table 12 and Table 14. These are awesome tables, really helpful.

Can you please let me know the name of the manual and whether they are still available for purchase?

Thanks!

Yo Unthrottled,
Sorry for this delay in responding. Bad vision days here.
Here are the 1990 Bronco Pre-Delivery Shop, Emission and Electrical & Vacuum Troubleshooting Manuals (EVTM), Partial by member Kingfish999 in Google Drive @ 1990 Ford Truck service manuals - Google Drive
&
1990 Ford Truck Emissions Manual.pdf by Ford via member 90.CaliBronco in Google Drive @ 1990 Ford Truck Emissions Manual.pdf
Suggest you download for faster scrolling and to use the table of contents index.

1990 Ford Bronco Brochure by Ford via Dezo's Garage @ https://www.xr793.com/wp-content/uploads/2020/07/1990-Ford-Bronco.pdf

Haynes Red Manual for 80-95 Bronco & F Series @ Hanes guide 80-96 bko f series.pdf found by BroncMom!


See my friend Fireguy50 (Ryan M) site @ Fuel Injection Technical Library » Home

 

[racrx]

update on 1990 bronco. met with the owner i bought it from to pick up some spare parts he promised me. I found out he had replaced the computer due to some issues he was having. he still had a pic of the original computer, the replacement computer was the wrong one. so after getting the right computer and changing the fuel tank, fuel pump and sending unit because the fuel sat in it for years i got the bronco going and it runs and drives really well. Prior to knowing the computer was the wrong one i replaced the throttle position sensor, the map sensor and the idle air control sensor based on trouble codes from the wrong computer. also the OD light always stayed on, now it works as it should. thanks for all the prior input.

 

[goodO1boydws]

update on 1990 bronco. met with the owner i bought it from to pick up some spare parts he promised me. I found out he had replaced the computer due to some issues he was having. he still had a pic of the original computer, the replacement computer was the wrong one. so after getting the right computer and changing the fuel tank, fuel pump and sending unit because the fuel sat in it for years i got the bronco going and it runs and drives really well. Prior to knowing the computer was the wrong one i replaced the throttle position sensor, the map sensor and the idle air control sensor based on trouble codes from the wrong computer. also the OD light always stayed on, now it works as it should. thanks for all the prior input.

That's GREAT news!
I'm sure you breathed a huge sigh of relief when you found the source of the actual problem was something stone simple like that.....right after you let out an an ear-splitting ARRRRRGH!!!!!