I have been trying to trace down a low power problem with the car. After about 20% throttle you can push the pedal down further but the car never accelerates any faster. Being pre-Lambda I put a O2 sensor into the exhaust and wired up a cheap A/F meter. What I found was that at idle the motor runs very rich, and as RPMs go up the engine runs lean. It's as if the fuel isn't increasing as more air goes into the motor. So off idle the car drives fine but the further you push the gas pedal down the more lean the motor runs. I pulled the intake boot and checked, the air flow plate moves freely. What's the next thing I should check or do to get my fuel back? Thanks for any advice.

~Mike

Hi Mike,

This thread, so far, has excellent replies. Not much I can add, except to reinforce (from experience) the notion a cheap AFR may not work well for diagnostics for the reasons 81 gives.

I think I may have the same setup you do -- 79 non-lambda EGR. More from curiosity than a symptom like yours, I added a narrowband sensor for a test and with it discovered that without a feedback system it really works much like a light switch with the normally wide mixture variations a k-jet yields under actual driving loads. The conclusion I came to was a wideband meter was needed for what I wanted to see.

Here are a couple visuals from my 79, and one jar-squirting video on the bench that is not mine.

Using the K-jet Fuel Pressure Test Kit

Injector Spray Video



I'm curious how this all came about for you, or whether you got the car with this behavior.
--
Art Benstein near Baltimore

A bus is a vehicle that runs twice as fast when you are after it as when you are in it.

Thank you everybody for the advice. I'll start reading the problem solver book once it's downloaded.

I purchased the car this way, sort of. The car always had a dead spot in the power band between 2,000 and 4,000 rpm. In searching through some shop books I discovered that the car must have gone to cali at some point in it's lifetime as it was a mix of federal and cali emissions equipment. Since I was trying to trace out a vacuum leak I returned the car back to stock (fed emissions) and in the process lost what little power on the top end I had. (of note: I had to replace the cracked intake hose with the restrictor neck with a straight through piece) I know the narrowband isn't entirely accurate but I was hoping it would give me a direction to look. (of course it figures that I just sold my LC-1 wideband) I've checked the ignition timing and it's set correctly for idle and does increase with engine vacuum. Checking the cam timing, the fuel pump and sock, and fuel pressure rise is next. Off to get a fuel pressure kit.

~Mike

Ideally a kjet fuel pressure gauge. About $100 at places like Harbor Freight. Otherwise, pulling the injectors, sticking them into bottles, and running the pumps with the engine off. Move the air meter to check fuel flow.

Be careful with the intake boot. They can tear or split easily.

It doesn't take much change in mixture to make an O2 sensor go full scale. If there is no missing above idle and no black smoke at idle, the mixture may not be that far off.

I would check ignition and belt timing. See if ignition advances as you manually open the throttle. If the belt moved one notch, you could have smooth running but no power.

Have you check for the quantity of fuel delivery? Could be a clogged filter or a in-tank filter sock, the in- tank pump. The main pump could be weak or starved.

Phil

Try this...download the Volvo Problem Solvers Manual Advanced Edition



http://www.volvowiringdiagrams.com/?dir=volvo/Trouble%20Shooting%20Guides

also if you tab up to Home on that page there is a Download for K-Jet

http://www.volvowiringdiagrams.com/?dir=volvo/K-Jetronic