Chugging, hard start, dies on acceleration... you tell me.

[LoveThySpatula]

Thank you all for your suggestions, I will be delving in deep into this issue this weekend (or when I find the time) and I'll get back to you all with updates.

And thank you all for being very helpful, especially to accommodate a newbie!

The fuel pickup tube may actually be the cause because I know that the pump has been fiddled with due to the dust cover being all funky and installed improperly - that will be where I will start.

As to there being multiple problems at once... I'm almost certain this has something to do with it, but I'll be starting with a solid fuel pump and line inspection.

[LoveThySpatula]

Finally got some time to work on the car - they've been working us to death at the People's Republic of Boeing.

I've found nothing wrong with the fuel system - pulled the pump and checked it out. Everything looked ok, no pinched or collapsed hoses. Bottom of the tank looks clean enough - couldn't access the screen though due to the tank being full. Maybe I'll run it low and check it.

Anyways, I found a nasty vacuum leak around the tubes that go from the throttle to the manifold and, get this, the bolts were loose! I tightened them up and the leak was lessened, however, it's still leaking. I'll be ordering some new gaskets and replacing those - hopefully that takes me one more step in the right direction.

Side note - she started up very easily after sitting in the garage for six days. Got her all warmed up and shut her off just to test the hot start deal. Still has a hot start issue as well - I'm hoping the gasket may have something to do with it but I'll keep you guys posted.

[LoveThySpatula]

Well guys got the new "intake" gaskets installed and the vacuum leak seems to have subsided for the most part. The no acceleration issue seems to have been unaffected.

I'll be following nightfire's advice regarding checking the WUR / CPR system for issues.

I did find another odd item that may or may not be related. It appears that my injectors are loose - they all have a slight amount of play in them. I will be tightening these down slightly to see if anything changes.

Last question of the day... Would a faulty ignition coil possibly be giving me these issues?

Thanks

[NightFlyer]

I did find another odd item that may or may not be related. It appears that my injectors are loose - they all have a slight amount of play in them. I will be tightening these down slightly to see if anything changes.

Last question of the day... Would a faulty ignition coil possibly be giving me these issues?

Thanks

Not sure what you mean by "the injectors are loose," whereby tightening them down would resolve the issue. The injectors are held in the bungs via a rubber boot and metallic clip. If either are bad, it can result in a vacuum leak around the injectors. To check, spray your targeted blasts of carb/throttle body cleaner at the injectors while the engine and run and note any surges in engine RPM resultant of doing so.

It's possible that your problem is ignition related, but highly improbable. As Dave Swingle likes to say, it's usually a fuel problem with our cars. That said, it doesn't hurt to confirm spark (you want a nice blue arc, as opposed to a yellow or white arc), and pull and plug and check it to get a read on what's going on inside the combustion chamber.

First, confirm that you truly don't have any more vacuum leaks (and especially around the injectors). Then, confirm the operation of your vacuum systems - both WUR/CPR and ignition distributor advance. Next, pull the fuel lines off the WUR/CPR and inspect, clean the filtration screens as is necessary. After, confirm spark while the engine is running, and after shutting it down, pull a plug and see if you can't get an idea of what's going on in the combustion chamber that might help us better zero in on the offending culprit.

It's also possible that your fuel accumulator suffered a very rare complete failure, but that's also highly improbable.

You can test the accumulator if you so desire by pulling the rear relief hose off the accumulator's barbed fitting, blocking off that hose, sticking a piece of loose hose on the barb (doesn't have to be a tight fit) and running the other end to a small bucket/catch container. Then jump the fuel pump on for roughly a minute or two. If the accumulator is fully functional, no fuel should come out of the barb/hose. If the accumulator is worn but still functional (although not as good as new), you may see a few drops/dribbles of fuel, but nothing dramatic. If the accumulator has suffered a complete failure (rare), then you'll experience a steady stream of fuel coming out the hose/barb, in which case, you'll need to replace the accumulator with a new one.

So, that's the order in which I'd start trouble shooting things,

We'll then go from there.

Don't make the mistake that most owners do and throw new parts at the problem until something sticks/works. Actually take the time/effort to diagnose the problem properly, and then you can get it fixed without otherwise spending money on a bunch of parts that you really didn't actually need.

Best luck

[LoveThySpatula]

Thanks for the info nightflyer.

What you say about the injectors makes sense... I wasn't sure how these are mounted thus my curiosity.

I'm fairly certain the ignition system is good, I checked everything out - good spark, everything is plugged in, spark plugs look great. I checked everywhere for more vacuum leaks (at idle it revs high then low rinse, and repeat - typical vacuum leak symptoms) but was unable to find any. I had the motor running and was taking off the airbox when I remembered I forgot to check out the frequency valve from a previous suggestion. I unplugged it while the car was idling and all of the sudden the idle cleared up and the motor was able to rev, even at wide open throttle. Now I thought this may have been related to the fact that the motor had warmed up so I drove it around for about a half hour then parked it for about two hours. Came back out and it seems to be doing well - still has a hot start issue but it appears the frequency valve may be faulty...

Will the vehicle be ok to drive without the frequency valve connected? Could this valve cause my peculiar running condition?

Thanks much.

[NightFlyer]

Frequency valve is a part of the lambda system, the purpose of which is to balance out the AFR so as to reduce emissions and provide maximum fuel efficiency. The frequency valve controls line pressure in the fuel distributor via instructions it receives from the lambda ecu, which operates in a fixed (open loop) or dynamic (closed loop) program mode. In closed loop operation, the ecu interprets signals it receives from the O2 (oxygen) sensor, which takes readings of the exhaust stream from its mounted location within the exhaust pipe.

The fact that you're idling and running fine without the frequency valve functioning at all suggests that your CO/AFR adjustment is set to run rich.

If you still have a catalytic converter as a part of your car's exhaust, running the engine rich over a prolonged period of time will eventually plug/clog the converter, in which case you'll either need to hollow it out, eliminate it from the system all together, or replace it. Running rich will also wear out your spark plugs and O2 sensor much quicker than they ordinarily would, not that you'd be all that concerned about the O2 sensor if you were choosing to run lambda-less. If the piston rings are worn, running rich can also lead to a condition known as bore washing, whereby the access fuel will eventually begin to contaminate the engine lubricating oil, and thus necessitating more frequent changes of the engine oil.

Aside from all that, running rich will obviously decrease your fuel economy/efficiency experienced.

Thus, it's really up to you to decide what you want to do.

Complete failure of the frequency valve is somewhat rare. Usually, whacking it with a hammer is enough to un-stick it and get it working again.

While the valve could be your problem, it could also be the lambda ecu, O2 sensor, or the system relay.

When operating normally, you should be able to hear the frequency valve buzzing - if not, then you may not be getting power to it, in which case, you'd check the system relay.

First things first though - did you ever confirm proper operation of the vacuum systems on the CPR/WUR and electrical distributor? Personally, I'd start there before digging any deeper into the lambda system. Just because you're seeing a positive response when experimenting with the lambda system, it doesn't necessarily mean that you have a problem with the system.

After confirming proper vacuum systems operation, I'd check the relay that drives the lambda system - it's the fourth one from the left in the top row, or number 31 in the diagram below.

Best luck

[LoveThySpatula]

Frequency valve is a part of the lambda system, the purpose of which is to balance out the AFR so as to reduce emissions and provide maximum fuel efficiency. The frequency valve controls line pressure in the fuel distributor via instructions it receives from the lambda ecu, which operates in a fixed (open loop) or dynamic (closed loop) program mode. In closed loop operation, the ecu interprets signals it receives from the O2 (oxygen) sensor, which takes readings of the exhaust stream from its mounted location within the exhaust pipe.

The fact that you're idling and running fine without the frequency valve functioning at all suggests that your CO/AFR adjustment is set to run rich.

If you still have a catalytic converter as a part of your car's exhaust, running the engine rich over a prolonged period of time will eventually plug/clog the converter, in which case you'll either need to hollow it out, eliminate it from the system all together, or replace it. Running rich will also wear out your spark plugs and O2 sensor much quicker than they ordinarily would, not that you'd be all that concerned about the O2 sensor if you were choosing to run lambda-less. If the piston rings are worn, running rich can also lead to a condition known as bore washing, whereby the access fuel will eventually begin to contaminate the engine lubricating oil, and thus necessitating more frequent changes of the engine oil.

Aside from all that, running rich will obviously decrease your fuel economy/efficiency experienced.

Thus, it's really up to you to decide what you want to do.

Complete failure of the frequency valve is somewhat rare. Usually, whacking it with a hammer is enough to un-stick it and get it working again.

While the valve could be your problem, it could also be the lambda ecu, O2 sensor, or the system relay.

When operating normally, you should be able to hear the frequency valve buzzing - if not, then you may not be getting power to it, in which case, you'd check the system relay.

First things first though - did you ever confirm proper operation of the vacuum systems on the CPR/WUR and electrical distributor? Personally, I'd start there before digging any deeper into the lambda system. Just because you're seeing a positive response when experimenting with the lambda system, it doesn't necessarily mean that you have a problem with the system.

After confirming proper vacuum systems operation, I'd check the relay that drives the lambda system - it's the fourth one from the left in the top row, or number 31 in the diagram below.

Best luck

Thanks for the info. I think I just got excited when I got a response from the frequency valve being unplugged - this is a pesky bug in the system and a response after digging for a while was welcome. I have not properly tested the Control Pressure Regulator, I was actually on my way to do that when I messed with the frequency valve. On a side note, the CPR appears to have been replaced - it is definitely not factory, but it could have been 20 years ago for all I know. However, I will get to testing that when I get back to having some time.

I believe a previous post suggested I remove all of the vacuum lines from the CPR and see if anything changes?

Thanks again

[NightFlyer]

I believe a previous post suggested I remove all of the vacuum lines from the CPR and see if anything changes?

To definitively test the CPR/WUR requires a Bosch K-Jet inline pressure gauge, and then comparing the readings to those of normal operations as laid out in the workshop manual.

What I'm having you do is just confirming the proper operation of the two vacuum systems that intentionally affect how the engine runs.

Those systems work like this:

When you first start the engine cold, vacuum from the multi-port switch in the y-pipe (under the intake) is directed to the warm-up regulator / control pressure regulator (WUR/CPR). Once the running temperature reaches 104F, the multi-port switch redirects the vacuum to the solenoid hanging off the mixture unit behind the fuel distributor. When the engine is idling, the idle micro-switch is activated (closed) and instructs the solenoid to hold the vacuum there within the solenoid. When the the engine is under throttle, the idle micro-switch is disengaged (open) and causes the solenoid to actuate and release the vacuum being held there onward to the distributor in order to cause the vacuum advance of the timing.

Vacuum advance at the distributor should only be present when the running temperature of the engine is above 104F AND when the engine is under throttle. At all other times, there should be no vacuum advance at the distributor - NEVER when the engine running temp is below 104F (whether at idle or under throttle) and NEVER when the engine is at idle.

Test each system (CPR/WUR and electrical distributor advance) separately. To confirm operation, you simply pull the vacuum lines off the WUR/CPR and the electrical distributor's vacuum chamber and/or vacuum solenoid and check for the presence/absence of vacuum during the various stages of engine operation, making sure that it's present when you want it to be and not present when you don't want it to be.

Essentially, you're just making sure that the three port thermal switch is operating as it should, and that the distributor is being vacuum advanced only when it should be.

If both systems check out, we'll assume that pressure in the CPR/WUR is OK and move on and look at the lambda system, unless you have the Bosch K-jet pressure gauges handy, in which case, you'd want to confirm your pressures before moving on.

Personally, I think you're on the right track in suspecting the lambda system, but we'll walk though the steps just to make sure and avoid any unnecessary parts expenditures.

As both the CPR/WUR and lambda system affect fuel line pressure, it's very easy to mistake a true fault in one as being a fault in the other, which is why you have to diagnose these two things separately, but always in conjunction with one another (unless the symptoms are clearly indicating one over the other), if that makes sense.

Best luck

[LoveThySpatula]

Vacuum advance at the distributor should only be present when the running temperature of the engine is above 104F AND when the engine is under throttle. At all other times, there should be no vacuum advance at the distributor - NEVER when the engine running temp is below 104F (whether at idle or under throttle) and NEVER when the engine is at idle.

Test each system (CPR/WUR and electrical distributor advance) separately. To confirm operation, you simply pull the vacuum lines off the WUR/CPR and the electrical distributor's vacuum chamber and/or vacuum solenoid and check for the presence/absence of vacuum during the various stages of engine operation, making sure that it's present when you want it to be and not present when you don't want it to be.

Essentially, you're just making sure that the three port thermal switch is operating as it should, and that the distributor is being vacuum advanced only when it should be.

And it appears that the CPR / WUR are working properly. I had no vacuum at the distributor's vacuum chamber at start up, unless under load. However, vacuum was present after the engine got hot - which means the thermal switch is operating as it should.

So at this point, any suggestions of where to look next?

[NightFlyer]

And it appears that the CPR / WUR are working properly. I had no vacuum at the distributor's vacuum chamber at start up, unless under load. However, vacuum was present after the engine got hot - which means the thermal switch is operating as it should.

So at this point, any suggestions of where to look next?

When vacuum should be present at the CPR/WUR: only after a cold start up, and only for the first few minutes of running (until the engine coolant temp reaches 104F).

When vacuum should be present at the electrical distributor's solenoid: only when the engine coolant temp has reached 104F or higher.

When vacuum should be present at the electrical distributor's vacuum chamber: only when the engine temp has reached 104F or higher AND during open throttle events (both condition must be met - if only one is met, then there shouldn't be vacuum here). There should NEVER be vacuum here at idle ever (idle micro-switch engaged/closed).

Assuming that you tested everything correctly, and that everything is working properly, then we'll move on to the lambda system.

Based on what you've already described, you're going to want to check the lambda relay in the fuse/relay compartment. Swap it with a known fully functional/operational lambda relay, and then with the system fully hooked up (nothing unplugged) see what you get and if it's different. Note that the lambda relay is a special one and NOT interchangeable with the regular/typical relays. Do you hear the frequency valve buzzing at all? If not, then use a meter to see if there's power on the line at all. If there is, then try smacking the valve with a hammer to unstick it. If there isn't, then figure out why and remedy the electrical problem (this could be a lot of things, including corroded pins in the connectors, loose/backed-out pins in the connectors, something with the pins in the relay socket, bad RPM relay, bad ground, etc).

Report back once the condition of the frequency valve is known.

Best luck