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1990 Bronco XLT 5.8L
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Discussion Starter #1
So I have looked everywhere and not been able to find what I am looking for ...
I have a 1990 bronco 5.8L it sat for a few years but was told it was running before it was parked. It would not start.
I have replaced
solenoid
starter
battery
fuel pump
fuel filter
and now running into Fuel pressure at 40psi but dropping down to 22 with in 10 seconds. I can get it started if I spray Starting fluid in it but only while starter fluid is present. At first it did not crank bad battery then it cranked but would not turn over so I replaced the solenoid and starter . Then it cranked and turned over but no start and fuel pump was not kicking on, so i replaced the pump and fuel fliter, but now I am not holding pressure. I have checked my fuel shut off switch , EEC has power , I have spark and feel like the only solution could be bad fuel injectors but was hoping to get some input if I should check something else?
 

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Hi @Hsdirty1 , welcome to the site..For future reference, make sure to fill out all the details about your Bronco under your profile..

First thing, hit pause on replacing parts..I see you've checked the fuel pressure, but have you checked for codes yet?

The EEC may have power but it also might be bad. So once you check the codes it would be a good idea to pull that and look for any signs of corrosion.

Good luck.
 

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1990 Bronco XLT 5.8L
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8 Posts
Discussion Starter #3
Hi @Hsdirty1 , welcome to the site..For future reference, make sure to fill out all the details about your Bronco under your profile..

First thing, hit pause on replacing parts..I see you've checked the fuel pressure, but have you checked for codes yet?

The EEC may have power but it also might be bad. So once you check the codes it would be a good idea to pull that and look for any signs of corrosion.

Good luck.
It is my understanding that since I had to replace the battery that it would not have any codes stored and reset the computer?
 

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It is my understanding that since I had to replace the battery that it would not have any codes stored and reset the computer?
Depending on how long the battery was disconnected you may still have stored codes. Either way, you should still crack the EEC to check for any issues.
 

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1990 Bronco XLT 5.8L
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8 Posts
Discussion Starter #5
Depending on how long the battery was disconnected you may still have stored codes. Either way, you should still crack the EEC to check for any issues.
Thank you for the quick response @jermil01 checked the EEC and there is no signs of corrosion I sprayed wD40 for good connection and current. I tried to get a code reading but my tester never lit up? Also I checked my pressure regulator and it did not have fuel up in the vaccum line.
Any other suggestions?
 

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No signs of corrosion in the EEC is a good thing, but you really don't want to be using Wd40 on those connectors, if anything just a little dielectric grease..

If you're not get any code reading there could be a ground problem with the STI (self-test-input) check to see if you can find any issues with the wiring.
 

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1990 Bronco XLT 5.8L
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Discussion Starter #7
Thanks again @jermil01 I will re-run that STI test tonight after work and see if I can get any codes to spit out! I pulled the battery to put a charge on it over night first then I actually had a battery I threw in but wouldnt hold a charge either then I actually bought a new battery so it was pulled a few times. However it sure would be nice if a code could steer me in the right direction and simplify something.
 

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Thanks again @jermil01 I will re-run that STI test tonight after work and see if I can get any codes to spit out! I pulled the battery to put a charge on it over night first then I actually had a battery I threw in but wouldnt hold a charge either then I actually bought a new battery so it was pulled a few times. However it sure would be nice if a code could steer me in the right direction and simplify something.
you're welcome. Wish I could offer some more suggestions. Maybe some other folks will come along with some ideas. This likely isn't the problem, but what condition are your battery cables in, any issues with corrosion, particularly around the ground cables?

Make sure to post up what you find.
 

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1990 Bronco XLT 5.8L
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Discussion Starter #9
Well good news @jermil01 my battery cables are good to go and I was able to pull 2 codes (22) & (11) but not sure what they mean going to search the forums and see what I can find it!
 

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1990 Bronco XLT 5.8L
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Discussion Starter #10
So if I read the guide right (11) = system pass (22) X X X MAP/BP sensor out of self test range. So does that mean my map sensor is faulty?
 

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95 Bronco, 351W, E4OD, 4.56 gears, 35x12.50x15 Patagonia MTs.
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327 Posts
So I have looked everywhere and not been able to find what I am looking for ...
I have a 1990 bronco 5.8L it sat for a few years but was told it was running before it was parked. It would not start.
I have replaced
solenoid
starter
battery
fuel pump
fuel filter
and now running into Fuel pressure at 40psi but dropping down to 22 with in 10 seconds. I can get it started if I spray Starting fluid in it but only while starter fluid is present. At first it did not crank bad battery then it cranked but would not turn over so I replaced the solenoid and starter . Then it cranked and turned over but no start and fuel pump was not kicking on, so i replaced the pump and fuel fliter, but now I am not holding pressure. I have checked my fuel shut off switch , EEC has power , I have spark and feel like the only solution could be bad fuel injectors but was hoping to get some input if I should check something else?
Is this pressure with or without the engine running?
 

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Registered
95 Bronco, 351W, E4OD, 4.56 gears, 35x12.50x15 Patagonia MTs.
Joined
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327 Posts
So if I read the guide right (11) = system pass (22) X X X MAP/BP sensor out of self test range. So does that mean my map sensor is faulty?
If that's what the book says, yes. I would check the resistance of the sensor to compare against a normal baseline to verify.

 

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1990 Bronco XLT 5.8L
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Discussion Starter #13
Is this pressure with or without the engine running?
Can't keep it running unless spraying starter fluid. So this was not running going to run those tests tonight. I have my dad coming over to help he is an electrician and has much better understanding of this area than I do! Thanx @twofortyz
 

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Glad you were able to chase down the codes. I'm pretty sure the bad MAP sensor could contribute to the no-start/hard-start condition you described. But as @twofortyz suggested you'll definitely want to test it before swapping out.
 

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95 Bronco, 351W, E4OD, 4.56 gears, 35x12.50x15 Patagonia MTs.
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327 Posts
If your fuel pressure drops when it's not running, I'm assuming this is when the fuel pump turns off. You have a slight leak I'd guess, my trucks have held pressure for several minutes when I tested them. Most likely an internal leak, old injectors tend to stick open from deposits.

Check the pressure when it's "running." and see how it looks. Also, check pressure with and without vacuum hooked up to it, there should be a difference. Try 15 inches of vacuum vs none, there should be a difference in fuel pressure. Cycle the ignition to run the pump several times if necessary.
 

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If you have a vacuum pump/gauge, you should be able to check your MAP sensor with the key on and engine off to make sure its working properly. I don't have my manual handy, but its a test that should be listed in any relevant Haynes or Chilton manual. Depending on the year, it could be a a voltage output, or frequency output. The earlier voltage type can be checked with a multimeter, the later frequency type can be checked using a spare aftermarket tachometer set to 6cyl
 

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1990 Bronco XLT 5.8L
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Discussion Starter #17
So the computer is definitely toast. It had a couple pieces in it that looked to be exploded along with at leat one of the EC's down a leg and tons of corrosion, it was actually even full of mod dobber nests. That will be in today, i will throw it back in and see if that fixes the problem or if it was just another piece of the puzzle ! Thank you for all your suggestions!! I will keep ya posted!
 
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