I have a howell tbi on a 4.2 in "83" cj7 and am pretty happy with it but it backfires when I decelerate. It also surges just driving or holding the rpms at 1,500 or 2,000. What could be my problem?

I seem to be having somewhat of a similar problem lately. I'm running a Howell TBI on my 89 4.2 YJ and am having a backfire when decelerating, the engine also seems to be running very rich.

Speaking with the tech support from Howell, he stated that I should check the fuel pressue and insure that it's at or near 12 psi. He stated that there is no adjustment to lean out the mixture.

I don't have the surging problem you mention but I do have the backfiring. The ALDL isn't indicating any problems when I check for any codes.

Don't know if any of this helped but I sure do need to try test my fuel pressure.

I checked the fuel pressure and it was ok. I advanced the timing an other 2 degrees to 10 and I have no more backfire and it seems to help the surge.

Thanks for the info. I think it may be electrical.

In the other HTBI thread I mention the "other" sensors that often don't come with the kits.
The reason...the ecu looks for all inputs, VSS is obvious because it tells the ecu that the readings from the MAP sensor and the TPS are "real", but also it leans the mixture upon slowing down. The brake switch leans it faster.

They included these inputs so that drivability are the best.
When you exclude them, those areas suffer with odd problems.

VSS and brake switch inputs are huge for best performance, will they run OK without, of course, just know why they do funny things.

SD

Hey Superdawg, I spoke with Howell and they stated for an additional $175 I can order the additional components to make this system CA legal.

Do they mean these components you talk mention?

Perhaps you should talk with Howell again and this time ask them what that package includes..
Meantime read your instalation manual again and see if they have in there some things you either did not get or that MAY be hooked up if you have them..
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

BigJim, I installed everything that came with the kit and upto about a month or two ago ran fine. Now, it just seems to be running very rich. I bought a fuel pump gauge so that I can test the fuel pressure and I also will replace the fuel filter.

I did run the jeep extremely low not too long ago and maybe sucked up a lot of dirt from the bottom of the tank.

I fixed my problem. I advanced the timing to 10 degrees and it runs great and no backfire. No surge. Runs great!