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+--- Thread: 5.0 backfires - problem solved! (/thread-2997.html)
5.0 backfires - problem solved! - SC74 - 12-04-2011
I piddled on this some yesterday and figured out that the trouble starts as soon as the temp hits 150* - not even hot, warm at best. It has plenty of power before it reaches 150* (which isn't long) - I dug a hole in the yard when I pulled up the the mulch pile - no hesitation and no backfiring. As soon as it hits 150* it starts puttering - can't even touch the throttle without it backfiring and most likely cutting off. I tried to limp it back to the concrete going 10-15 ft at a time and it stalling.
After getting it back on the concrete I let it sit and would key-on every once in a while to see the temp reading. I tried several times while it was 150* or just over and it just stuttered and backfired. I let it get down to about 130* and it ran perfect until the temp got back to 150.
I'm thinking it has to be a sensor from when it changes from "cold choke" mode to normal operating temperature mode.
5.0 backfires - problem solved! - johnpaulgolf - 12-04-2011
Ok this might sound crazy but have had this happen to me on a 5.0 Mustang after putting new fuel injectors and intake and blah blah blah :xyxthumbs:
So if the fuel lines get hot (leaning against something) the fuel (gas) will boil and cause "air" pockets and cause backfires and rough idle ect.
On the Bronco (non FI) I covered all fuel lines that came in close contact to hot surfaces.
Does not seem like I can explain myself right this morning ... my retardness is really acting up this AM
cratchhe:
5.0 backfires - problem solved! - SC74 - 12-04-2011
that makes perfect sense JP... I even cracked my fuel cell to make sure the vent wasn't clogged. I do have some SS fuel lines running close to the pass side headers. I will pull them up and out of the way to see if it does anything different.
5.0 backfires - problem solved! - SC74 - 12-04-2011
While splitting some firewood to burn tonight I decided to let the bronco idle up and get warm to see if moving the fuel lines away from the header would help.
It does seem to help - I moved both the supply and return up and away from the header and let the motor idle up to 180*. It did backfire on me SOME when I idled it up - even did a small power brake in rev. and forward. It's not 100% cured, but I think I'm on the right track with the fuel lines. No where else do they get near the exhaust, but I noticed something else....
While it was idling I held the supply line (flexible SS line) and you can feel the fuel in it. I noticed it was not a continuous supply - it would have a pause in it - then pressure for maybe 10 sec and then pause for 1 or 2 sec. Is this normal? Maybe I have a fuel pump issue???
5.0 backfires - problem solved! - johnpaulgolf - 12-04-2011
I used to run an adjustable external fuel pressure gauge. That would give you the answer on that and the ability to adjust your pressure if needed. Not expensive an a good gauge to have.
5.0 backfires - problem solved! - broncosbybart - 12-04-2011
If fuel supply is sporadic, that is not right. If you have a fuel pressure gauge, hook it up to the fuel rail fitting (it is a shrader valve like a valve stem for tires). Your fuel pressure should be about 40lbs and should not vary sporadically.
5.0 backfires - problem solved! - blazinchuck - 12-04-2011
he may not have the shrader valve...i had to lose mine when plumbing my system. i recently got one from lkq that will work. took a while to find a fuel rail with reg,fuel ports,etc all on the pass side. i just need to install it
5.0 backfires - problem solved! - broncosbybart - 12-04-2011
how did that happen? curious. on my 2 projects I was able to keep them (1 with HO mustang rails and 1 with Explorer rails).
5.0 backfires - problem solved! - SC74 - 12-04-2011
Chuck is right - I don't have the shrader valve. I have a SS line that hooks up to the fuel rail at the weird ford fitting. I have considered putting an in-line permanent fuel pressure gauge in but didn't think it would be a "need-to" basis.
JP - you were carb right? I've seen that done on carbs but not efi.
5.0 backfires - problem solved! - johnpaulgolf - 12-04-2011
SC74 Wrote:Chuck is right - I don't have the shrader valve. I have a SS line that hooks up to the fuel rail at the weird ford fitting. I have considered putting an in-line permanent fuel pressure gauge in but didn't think it would be a "need-to" basis.
JP - you were carb right? I've seen that done on carbs but not efi.
Robert my Bronco was carb yes ... But in my younger days I played with fox body mustangs from the late 80's that's when I would run that gauge in line to make sure things were ok with my fuel after installing bigger injectors TB's ect