Backfire through intake

**Darrenmb** · 10-25-2021, 04:06 PM

Just one! No other issues, copying and pasting from the drivetrain forum where my initial problem was posted

oday I had a glitch!!! Think I may have a fuel
Delivery problem, not a vss issue as originally thought,
I was driving along, coasting down to a stop and blipped the throttle, instead of the usual jump forward I got a backfire( through the intake) But other than the pop, nothing else, car didn’t stall, still has plenty of power etc, going to repost this in engine forum
For more traffic!

**Darrenmb** · 10-25-2021, 04:10 PM

Ok, hit post too soon, I am still having noise issues with my fuel pump, I am starting to think I am starving for fuel sometimes, time to do another catalog, and hope Fred can help me out ( hint hint) ��
I am in no rush as of right now, going to order some
New pre filters and another post pump filter,
Just as a recap, this in an a jag , has external fuel pump, so does anyone know of a good external pump that I can replace the jag one with?

***SSlowBoat*** · 10-26-2021, 10:00 AM

Originally Posted by Darrenmb

Ok, hit post too soon, I am still having noise issues with my fuel pump, I am starting to think I am starving for fuel sometimes, time to do another catalog, and hope Fred can help me out ( hint hint) ��
I am in no rush as of right now, going to order some
New pre filters and another post pump filter,
Just as a recap, this in an a jag , has external fuel pump, so does anyone know of a good external pump that I can replace the jag one with?

backfires thru intake are usually timing related, ie stretched timing chain, or opti issue.

**Darrenmb** · 10-26-2021, 02:36 PM

Timing chain has less than 2000 miles on it, so does the opti, Opti was gone through by optidoc, or whatever his name is on eBay, Herrington, or something like that, not that it still couldn’t be the issue, but it was a single pop through intake, never happened before and hasn’t happened since, I did have some hiccups like torque converter was locking and unlocking a while back, but again, hasn’t done it since! Car runs fantastically! No cutting out or misfires at higher rpms, no codes present. Idle is as smooth as it probably can be with the hot cam and set at 750.
I have had issues with old jag engine doing same sort of thing, which is another reason I leaning toward fuel delivery, it’s the only thing that remains from original setup, and jags are notorious for rust in the gas tanks ( poor design, counter sink filler caps in rear fenders on each side, with a drain setup to get rid of rain water that blocks, then seal on gas cap goes bad with age, allowing water into tank, add to that ethanol fuel and odds are stacked against me!!!) this is why I have prefilters installed before the pump and the stock big filter after it.
When the week gets here I will tie the laptop in and go for a drive, hopefully something shows up in the scan!

**Darrenmb** · 12-30-2021, 10:31 AM

Just an update….
This week was supposed to be the week I did the gear swap, however things never go as planned! Was out driving Christmas Eve and she backfired again, and car started bucking hard! I switched to other gas tank and she smoothed out but only for a few miles, then started doing it again, switched back to original tank and she was smooth again, took her home and parked her until yesterday.
Got up yesterday morning and went into garage, pulled spare out to look at the pre filters, wow! Jet black! So I cleaned them out and decided to try something!, I drained the right gas tank into fuel jugs and popped the fuel sender out to have a look see inside, ( this is all very simple on jag, there is a drain plug on bottom of fuel tanks and the sender is accessed by removing the tail light)
Side walls appeared to be i good shape, but bottom of tank was completely covered in crap, the sock for fuel pickup has collapsed in on itself.
Now, fuel tank removal on jag not so simple, bumper has to come off, body panels must be removed, etc, so instead of that I had a brilliant idea! I stuck my pressure washer wand in through the sender hole and blasted the crap out of it, with drain plug still removed the amount of junk that came out was horrific!, next I put a 3rd piece of rubber hose on my air gun from
Compressor and just kept blowing it out until no more water was dripping out, i reassembled everything and took her for a drive, she running fantastic again! After extended run I am satisfied that this is where my issue was! Next is tomdonthenleft tank! Of course that one is full!!!! If I can find my old fuel
Pump from the boat, I can use it to pump fuel ( through a filter) into left tank which is now at. 1/4 tank, being as each tank hold 12 gallons it should bring it down to where a couple cans will hold what’s left!

**Darrenmb** · 12-30-2021, 11:33 AM

Forgot to add pictures 3187A33A-3636-458B-BCDA-79D3F95FCF66.jpeg this is the crap that came out of the filters

**Darrenmb** · 12-30-2021, 11:34 AM

ADF7BC45-FD0A-439F-B69D-4CF42F1B6452.jpeg super easy access to sender

**Darrenmb** · 12-30-2021, 11:35 AM

BF6C9851-6E9F-47BF-BC59-317B0D72181D.jpeg all the crap that came out of the tank…. But not the leaves… lol

**Injuneer** · 12-30-2021, 01:27 PM

Glad you figured it out. The whole thing had me puzzled.

I wish I had the ambition (and youth) to go out and clean my Formula's entire fuel system. I would either have to cut a hatch in the package shelf to access the sending unit (somewhat complicated by rear roll bar braces), or drop the tank, which is pretty much out of the question for a driveway project.