no_name

I have a stock 1985 GSL with rats nest removed. It seems my car loses about 60% of its power above 100kmh (60mph).

Now up to 100kmh it accelerates fine ( minus a slight bogg once in a while), so does anyone have any idas on what the issue could be?

I did a quick search and no luck lol.

I am thinking the carb is the issue, also the fuel filter was jsut replaced today lol.

Thanks,

Ted.

trochoid

iTrader: (6)

Do you still have the cats?

cpa7man

iTrader: (2)

I was thinking clogged cat as well.

Jozay721

if u really use duct tape then that might be ur problem

no_name

That is what I was thinking too, but I have a newish (a few months old) main cat, and RB header so their are no pre cats.

Could their be a problem with the carb? Perhapse the intermediate circuit?

msimonov

iTrader: (5)

Running a header directly into a cat can destroy a cat pretty quickly. I went through 2 cats in 2 years with this setup.

It is is easy to check the cat. Just upbolt it from the header and then seperate the flanges with a scerw driver or something. Take it for a short ride. It will be loud. If you notice a big difference, unbolt the cat and shine a light in it. If the honeycomb is all melted together, your cat is cooked. A broom handle will knock the insides out of the cat, and your problem is solved until you have to pass emissions.

Kentetsu

I hate to ask the obvious, but how old is your fuel filter?

Rogue_Wulff

From the first post:
Misspelled, but I think he is trying to say it was just changed.

Clogged cat is a good possibility, as is a restriction in the fuel system. Could be a weak pump, crud in the fuel line, pickup tube partly blocked. Check for fuel flow at the carb, only way to rule out a flow issue.

Kentetsu

Ah, thanks man I totally missed that on my first pass through...

no_name

How do I check for fuel flow at the carb? ( I know it is a stupid question, and I probably already know how to do it, but better safe then sorry)

I will do further investigation into the cat. I just know it is going to be a pain in the *** to remove ( I have no hoist or air tools lol). With any luck the bolts will break off lol.

Rogue_Wulff

Disconnect the fuel line from the carb, place a large container (like a 1 liter soda bottle)under the line, and turn on the pump. See how long it takes to pump a liter of fuel. Over a minute, and you have a flow problem.

trochoid

iTrader: (6)

If your rats nest and air pump are gone, your oem cat is toast. Yes, the rusty bolts will break, snap, round off. Get a can of PB Blaster, a small propane torch and start working out on the weight bench. Or bite the bullet and take it to an exhaust shop.

cdrad51

A little oversimplified don't you think? especially since with the '85 he will have to bypass the fuel cut relay to have the pump on...

I can just see his next post "Guys I did a fuel volume test and there is no fuel coming out of the hose that goes into the carb! "

cdrad51

You mean the transition circuit? why in hell would that affect high rpm behaviour?

Like trochoid said, your cat is toast. And even if that is not the problem, it will contribute to it.

cdrad51

Hey, I have an idea. Maybe it's the "secondaries are stuck" epidemic that's going around.

All kidding aside, something worthwhile checking.

Rogue_Wulff

Ok, so I failed to mention the fuel cut relay However, I did NOT simply say "Turn on the key", opting instead to use the phrase "turn on the pump".
Was it oversight on my part? Or, could it be that I gave the person the benefit of the doubt, and assumed they were aware of the fuel cut relay? Don't ask me, 'cause even I don't know the true answer................

cdrad51

lol it's all good man, I'm just giving ya a hard time

But you know I'm right!!

trochoid

iTrader: (6)

I missed the 'newish cat' in your post. What type of cat did you install?

A quick check on fuel flow can be done several ways. Watch the sight glass on the front fuel bowl, rev the engine. Does the fuel level drop or stay centered in the glass? Another method is to jumper the pump and do the 'pee in the bottle' test.

no_name

Intresting. The newish cat I installed is OEM.

I will try to check the float bowl levels as I rev the engine and see how that turns out.

Also it is not jsut at high rpms, it is at low rpms too. Like 3000 rpm, or 6 000 rpm, as long as I am between the 40-90% thottle range I get very little power.

And transition circuit sounds more correct then intermediate lol.

cdrad51

Well anything above 2k rpm is main circuit, so don't worry about the transition or transfer circuit.

cdrad51

haha I like the time of my last post. 7:07. If one is on west coast time that is

Rogue_Wulff

9:07 Here in the real world

cdrad51

9:07? go to sleep old man!

Rogue_Wulff

I just finished off a cup of coffee, and debating another. I bet you go to bed earler than I do, even with the time difference..........

cdrad51

haha 1-3 am, usually...

I think we have hijacked the poor guy's thread enough now...