Seafoam issue?

Hi all,

My 1996 2.7 4x4 is throwing code P0420 (catalyst system efficiency). I decided to start with a seafoam treatment in the fuel tank and intake to give it a good clean. A few days ago, with about half a tank of gas in it, I dumped a whole can of seafoam into the tank. It died at a stoplight about 5 minutes after I did this. It restarted right after that but it has been running rough ever since and has actually died on me twice, particularly after sitting overnight. I filled the tank up the next day but it doesn’t seem to have made much of a difference.

I was under the impression that you can’t use too much of the stuff but maybe I was wrong? I’m worried I may have burned something up by using the whole can with so little gas in it!

Anyways, my first thought was that the seafoam might’ve moved some gunk into one of the fuel filters so I was going to start by checking and probably replacing both of them.

Any thought? Thanks!

 

Seafoam? Really? What about paint thinner? If you watched it on YouTube it must be true? Seriously though for the price of a few MECHANICS IN A CAN you can buy a decent OBDII scan tool to graph sensor performance and a laser heat gun to check catalytic converter temps.

 

I did it based on advice I got from a Toyota mechanic. Most people on here have been pretty helpful in the past, you seem to be an exception. Why even waste your time?

 

I've always had good luck with Seafoam in the past on a variety of vehicles. How many miles have you driven since you topped off the tank with fresh gas?

 

MagtechPA,

I’ve driven about 150 miles so far. Not through a full tank yet.

 

I've had seafoam pull stuff out of the tank and clog the fuel filter on a high mileage 4runner I had

 

How did you pull it into the intake, through a vacuum line? I'm wondering if it's something as simple as a vacuum leak.
On the Fords I've owned, I would always pull the main vacuum line off the brake booster and use it to slowly suck the Seafoam into the intake. It worked great but I always had to be careful that the hose was fully seated and clamped when I was done.

 

Yeah, through the brake booster line. I’ll double check it, but the issue started before I cleaned the intake with it. The first thing I did was run it through the fuel tank.

 

Yeah, I'll bet it knocked some gunk loose. How many miles?

 

133k

 

You could start with a fuel pressure test. That'll tell you if something got clogged

 

Okay, I’ll look into that. It would be nice to know before replacing as that second one looks like a pain to get to. Thanks!

 

Ooo yes you're 2.7 not 3.4 those 4cyl fuel filters are in the most inconvenient spot

 

Seafoam is nothing but a glorified Naphtha with isopropyl. It won't do anything bad or much of a good. There are much better products you can use.

 

Seafoam is good but I prefer B12 Chemtool as it is cheaper and far more potent... but I only use it in the fuel tank and on all my small lawn equipment. I use Seafoam for the intake through the brake booster line.

Like others have said it more than likely dislodged a bunch of buildup and restricted flow at the sock or fuel filter.

As long as you let the motor SLOWLY suck the Seafoam you're fine. I do 1/3 of a can and it takes about 10 minutes or so while never letting the vehicle to suck up enough to die. Shut the vehicle off for at least 15 minutes. Restart and enjoy the smoke show.

I'd replace your fuel filter and go from there. Or put more in the tank to try and dissolve the gunk its already dislodged. Or it may have coated your o2 sensor with carbon.

 

Have any dash lights come on? Although his remark was a bit sharp, the suggestion to get a code reader was actually a good one.

 

I dumped two cans of it in less than 5 gallons gas. Won’t harm (or help in my case) anything

 

You are going to need a decent OBDII scanner to diagnose this. My gut tells me you wiped out a O2 sensor.

As to your original issue of the P0420 code that has been discussed to death here. In short you are either going to have to replace the cat or mask the rear O2 sensor signal with a URD rear o2 sensor simulator.

This is THE least expensive way to "fix" the issue... apx. $120.00
https://www.urdusa.com/urd-rear-o2-simulator-2rz-fe-2-4l-3rz-fe-2-7l/

 

The P0420 code went off before I did any of this. As per advice I was given by mechanics in the past and the numerous forums I’ve read here, I decided to go with seafoam just to see if it might be a small issue with fuel/air mixture and a quick cheap fix. Apparently mine won’t be! But hey, it’s an old truck!

I don’t already have a good OBDII scanner and I don’t know anyone that has one. So, I’ve got two new OEM O2 sensors and a cat on the way and I will be checking the fuel filters ASAP.

 

Seafoam is for old 2 cycle boat engines using ethanol free gas. Get something with PEA like gumout multi system cleaner. I would change the fuel filter now that you have disturbed sediment. Good luck.