WA 2 FST

Hey guys,

Well my fuel solenoid is working fine, but there have been several instances locally of problems with these things sticking shut. A local shop owner called me today and told me I might not want to use my nitrous, and explained the problem.

I decided to go over to the shop and take a look at the issue.

Seems that the solenoid functions properly (as far as being activated), but the little neoprene/rubber tip on the bottom of the plunger is expanding significantly (in some cases, completely shutting off fuel flow even after the solenoid has "opened").

I saw 3 examples and one of them was really bad. I mean the rubber portion was totally deformed and protruding out compared to the way it looks "new", which is flush with the plunger housing...I saw several brand new plungers to compare.

We took mine apart and it shows some evidence of this, but not bad.

HOWEVER, the most disturbing thing was that two of these problem 'noids were BRAND NEW. Hadn't been on the vehicles in question more than 3 hours. Driven to the track and then boom. Both motors are toast. Both are significantly modified and running large amounts of spray.

I did not get a chance to dyno mine to see if the slight "swelling" of the rubber seal has caused enough of a restriction in fuel flow to adversely affect my A/F ratio. I know I'm getting fuel flow through there as the motor will bog during testing (nitrous bottle closed). I'm kind of feeling like chances are pretty good that it won't get worse (as again, the two problem 'noids were both brand new, so the rubber material must expand to its threshold almost immediately after being subjected to fuel pressure), but am just wanting to be very cautious about this.

Anyone ever rebuild their solenoids? Does TNT have a "kit"?

I know NX requests that you just send their 'noids back to them.

C5Noir

I wonder if it's best to start using NOS brand 'noids? They have rebuild kits and I haven't heard of near as many issues with them.

FRC21

What shop called you, speedworks? The NX fuel noids have also been having problems. I wonder if there is a new additive in the gas causing problems? :confused: I'm really starting to think about going dry, since I have not put my kit on yet.

WA 2 FST

Yes, it was SpeedWorks. They are working hard to find a good solution.

I know there are plenty of guys on here and elsewhere who run dry kits. As long as I've been around tuning forced induction on MAF controlled cars, I _personally_ do not trust the life and accuracy of the MAF sensor when its being subjected to nitrous.

The old dry kits that used a signal to the FP regulator to spike fuel pressure to the injectors were great. I prefer those over wet kits (just one less solenoid to malfunction, if no other reason). However, without a return line on these newer cars, this type of function is obsolete.

With regards to NOS solenoids...yeah, that may be the best and most permanent fix.

We'll see.

akw408

Interesting. Maybe it's time to check the fuel used in the car. How did you take your solenoids apart? And maybe we should ask TNT if they have a rebuild kit, I'd be surprised if they didn't.

WA 2 FST

RE: Fuel used

This is a very fair inquiry...however, all the parties involved have used different brands/types of fuel. The two vehicles that sustained engine damage used high octane race gas (leaded, I believe). On the street, they use 93 octane pump gas, but both of the new solenoids that had problems only had race gas in them (as they were driven/trailered directly to the track after the install!).

My car sees only Exxon/Mobil 93 octane.

The information I'm getting is that the material used for these seals is prone to expanding under pressure over time. However, for some it took ~20 miles or less to expand to the point of closing off the fuel supply. :(

I have sent TNT a very nice and thorough e-mail and have yet to hear anything back. It would be nice if they sell a rebuild kit (and hopefully with an improved seal on the plunger). I have my doubts, but will wait to pass judgement.

C5Noir

Good luck getting TNT to reply back to your e-mails. Best way is to call them. They're not punctual when it comes to e-mail.

akw408

How did you take your solenoids apart to look at the seals? Any special tools required?

WA 2 FST

Remove the top nut...this is easy, no tricks.

Then you will pull off the coil "cap". You'll see the large stem and at the base of it there are two very small "divots". NOS has a tool for their solenoids, but I don't believe it will work with these. :( You have to use some snap-ring pliers or a punch stuck in one of the divots to twist the stem loose. I saw one of the techs use a pair of pliers on the stem on a different solenoid they had in the shop. **However, he was using a pair that had no "teeth". You do NOT want to gouge the stem at all, and of course never grip the threads at the top.**

What I would consider doing is using the old "double nut" method on the threads of the stem and loosening it that way. The stem threads down into the base of the solenoid, so that's why you have to loosen and remove it.

Once you have loosened the stem from the base (there will be some fuel that comes out, so a shop rag underneath is handy), you want to carefully remove the stem. Turn the stem over, and on the bottom side you will see the plunger/seal. Be very careful with this so that it does not fall out. There is a tiny, tiny spring under there ... and you can easily lose this if everything comes apart before you're ready for it.

I will be happy to continue to update on this situation as I get more info.