EFI ISSUES FIXED?!?!?

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EFI ISSUES FIXED?!?!?

Postby broncomarc » Mon May 25, 2009 10:25 pm

After over a year of sporadic issue, I've had the best success with my fuel issue. Jason and I went to Harlan this weekend and my Bronco started running like crap again. As a last ditch effort I put a brand new fuel pump on it right before we left and I was still only getting 30 PSI to the fuel rail.

Then I started messing with stuff and I had a break thru! I disconnected the vacuum line that goes to the fuel pressure regulator and my pressure went up to 40! I capped the vacuum port on the regulator and I had a fantastic 3 days of riding with 0 EFI issues! The pressure wandered around 40 - 55 pounds all weekend. I thought 55 was too high, so I connected the vacuum line for a second. It dropped down to 30, then back to 40 when I unplugged it.

So, How does this thing work? Is the vacuum supposed to make it change pressure with engine speed? Could I have it connected to the wrong vacuum port on the manifold? Which port is it supposed to go to?

Would I be better going to an adjustable regulator? Any recommendations?
- Marc Reiter
1973 Bronco - http://www.broncomarc.com/bronco/

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Postby kesterkamp » Tue May 26, 2009 11:07 pm

run high pressure fuel lines and be done :biggrin:
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Postby broncomarc » Tue May 26, 2009 11:09 pm

Weird.. I thought I posted that to the BroncOhio forum. That explains the point of view in that post. Oh well.. You guys can take a crack at it too. :biggrin:
- Marc Reiter
1973 Bronco - http://www.broncomarc.com/bronco/

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Postby moabbs » Sat May 30, 2009 12:28 am

For what its worth and I know nothing about Broncos, thats a less than full size horse isnt it? Anyway, injected fuel pressure controled by vacumn is not controled by direct connection to the vacumn port but by at least one or more sensors that control the fuel rail vacumn regulator. I would consult a good repair manual or even a good parts book.It is possible to control pressure with a good quality regulator but only constant pressure not varied pressure. If all else fails and it runs ok than let it be.

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Postby broncomarc » Sat May 30, 2009 3:58 am

Wikipedia - Bronco, or bronc, is a term used in the United States and Canada to refer to an untrained horse or one that habitually bucks. It may refer to a feral horse that has lived in the wild its entire life, but is also used to refer to domestic horses not yet fully trained to saddle, and hence prone to unpredictable behavior, particularly bucking.


Yep.. sounds about right. :biggrin:



I bought a vacuum gauge. I'm going to test different ports to find how they are different.
- Marc Reiter
1973 Bronco - http://www.broncomarc.com/bronco/

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Postby moabbs » Sat May 30, 2009 11:26 pm

I was wrong about letting the pressure ride. The pressure has to remain constant at all engine conditions approx. 38lbs . This is achieved by multible information going to the ecm and it in turn regulating pressure through an electric vacumn control unit or something simular.

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Postby broncomarc » Sun May 31, 2009 8:44 am

I don't think the computer ties into it at all. All the diagrams I can find show the vacuum line connected directly to the intake manifold.

http://www.veryuseful.com/mustang/tech/ ... iagram.jpg
- Marc Reiter
1973 Bronco - http://www.broncomarc.com/bronco/

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Postby moabbs » Fri Jun 12, 2009 8:23 pm

Was in the Summit Racing parts catalog last night. They have a number of EFI regulators and pumps. Nothing else needed, vacumn, ECM, etc. Probably an easy way to go.

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