Why does the engine in my 1991 Suzuki Samurai cut out under load?

Answer 1

If your symptoms are it will idle, but can't rev up over about 2000 RPM with virtually no power, then odds are you have a defective catalytic converter. The core inside the coverter can break loose, and get lodged against the converter's output pipe.

When this happened to me (kind of like blocking a tailpipe with a potatoe) pressure built up so much inside the engine that it would blow off my PCV hoses!

How to tell if this is it:

1. Rap on the converter with a mallet. If the core inside is loose you will hear it rattling around.

2. Loosen the bolts that join the exhaust manifold to the downtube that leads to the converter. These are the bolts that are spring loaded to allow flex as the engine shifts when it revs. Start the engine...IT WILL BE VERY LOUD, YOU CAN'T DRIVE AROUND LIKE THIS...see if the engine will rev up again like it used to, now that you've given the exhaust an 'exit path'.

I think there had been a recall on some Suzukis about this, but it's probably long expired. ISTR the stock converter listed at over $600. I went to a local muffler shop and they cut out the old converter and welded in a replacement for half that.

Hope this helps, Paul.

i had this same problem with my 87 samurai it wasn't the cat even though my first guess was the cat there is a vacuum switch valve on carb that applies vacuum to secondary actuator diaphragm disconnect both vacuum line hook them together bypassing vacuum switch if this solves your problem either the vacuum switch is bad or the thermal switch is bad i just connected the vac lines together and didn't worry about solving the root problem this system is designed so that the engine has to fully warm up before the secondary will work so let the engine warm up before you rev the engine past 3000 rpms (mike)