hupp

I have been having problems with my shark. It started with a small flat spot during acceleration then one day it suddenly got worse - my shark would not even make it to 20mph. The WUR on my shark was incorrect - I have a 5-spd the WUR was for an auto. I also found a piece of debris in the small screen on the WUR inlet.

I ordered a rebuilt unit correct for a 5-spd, installed and began to test the system. When I applied vacuum, it would not hold. I had to continuously pump the mighty vac to maintain vacuum. My old WUR, which is spec'ed for an auto, would hold vacuum throughout the entire test when applied. Is there a difference between how each WUR should hold vacuum or should both hold? I'm assuming this rebuilt WUR deffective?

Off with the new and back with the old in hopes that removing the piece of trash solved the problem. Still a flat spot above 3500rpm, but a little worse.

jpitman2

Hupp, you need to get pressure readings of Control at the WUR, AND do delivery rate test -a problem in either will give low power - hot control ~45psi, delivery ~1350ml/30secs IIRC. Pretty sure that WUR should not leak vacuum at all. Is it a one or two vacuum connection unit? if the gasket between base and body is defective, screws not tight, or body faces damaged then a leak could occur. If you have it off, try blowing into it with fluid on the joint line and look for bubbles - easier to see than suck-in effect? DId it run any better with rebuilt WUR on it?
jp 83 Euro S AT 49k, BTDT

hupp

Pitman,

The new WUR is a rebuilt unit. Reason for the purchase was cold start issues and a bit of a lack in power around 4000rpm and up. Also a slight problem when hot starting. All components of the K-jet are new except the fuel distributer. (I replaced a bunch of stuff during my engine project.) The old WUR is part # '053 (for automatic) and the rebuilt is #'063 for manual.

Tested the old unit because of the problems mentioned above and found that cold control and warm control were both too high. (Which, according to the manual, can cause a flat spor during acceleration) Leak down and system all in check. After this test I decided to use the "tap down the plug" method to adjust the control pressure. I managed to get cold control closer to spec but warm control remained high.

Ordered the rebuilt unit intalled and tried to start the shark - no luck. Put the gages on and found that vacuum would not hold, cold and warm control way high. Colt at 3 bar and warm at 4.3 bar.

jpitman2

When mine went bad it would start with good cold control , but hot went to 60psi, no power. Blocked WUR inlet filter in the end. I dont know for sure if lack of vacuum will give high control - Dennis?
I would do a check for a blockage in return line - crack open WUR outlet - if no pressure drop, WUR is blocked; If pressure drop, close that, crack open next joint in return line - the one at the distributor, then do the return line at the tank top. When you find the first joint that DOES NOT produce a pressure drop, the blockage is in the line back one step. A bad main pressure reg in distributor can do this IIRC, but I havent seen it myself. If new unit gave high control, its either because of the lack of vacuum, or another blockage somewhere.....Suggest a copy of Ben Watson makes good reading when here...
john p 83 Euro S AT 49k

FBIII

I recently traded for Euro S with CIS woes. It came with a box of replaced items; WUR, Fuel distributor & cold start valve. Its missing a few things which are keeping me from trying to get it running at the moment. But in checking the replaced WUR it also does not hold a vacuum. The horizontal port holds a vacuum but the one on top leaks. Any idea what that leak would cause?

hupp

FBIII,
The top port on the WUR is atmosphere not vacuum. The side port is the port that should hold vacuum. Your WUR sounds normal.

Pitman,
I do not believe that the lack of vacuum caused the high control pressures. In fact, lack of vacuum should cause the pressures to be low since when vacuum is applied the pressures increase.

The old WUR was slightly out of spec (.2 bar high), but I've heard that this is enough to cause a lean mixture. The new WUR had way high cold control at 3.4 bar and warm at 4.2 bar - obviously wrong. Plus it would not hold vacuum. I found the piece of trash on the old WUR inlet screen when I removed the feed line adapter to transfer it to the new WUR. After testing the new and finding the specs way out I removed to send back and put the old back on. She runs again and can make it over 20mph, but has a flat spot above 3000 rpm. This tells me that the trash (now removed) was preventing me from even doing 20mph and the acceleration flat spot is still being caused by the slightly high warm control.

hupp

One other thing:

I've read that some vacuum leaks can tend to develop after backfiring. Since my shark backfired through the manifold a few times due to the trach in the fuel line it may be possible that I now have some leaks. I'm assuming I should check all the lined under the intake/around the throttle body. Any other suggestions?

jpitman2

Scott, I have heard that backfires are especially bad for CIS as they can damage the air plate area. I would check that the airplate at rest is in the correct place, and not binding in its movement anywhere. Also check all rubber hoses for leaks and correctly fitted, and the big joiner hose from throttle body to spider, and ign distributor connections, although these should not leak much volume. I found it not too difficult to remove the spider body - easier than pulling several inlet runners anyway, and then you can see all the hose connections easily. I still think you should find the source of the high control- if its in the WUR, open the outlet union, you should NOT see a pressure drop or much fuel leak if it is there. If you do see a pressure drop, the problem is further downstream - that line goes to a union on the fuel distributor, and then back to the tank - check the tank return line for flow. Based on my sad experience (terminal damage), I would leave tapping the pressure regulator as a VERY last resort after all other possibilities for pressure problems have been exhausted. Adding home made gaskets to the joint in the WUR can lower the control pressure because it effectively lifts the regulator above the springs.
FBIII, the top port should have a vent line going to the throttle body, or at least somewhere under the spider - find the CIS hose diagram, it is shown there IIRC.
jp 83 Euro S AT 49k

hupp

Pitman,

Air sensor plate is ok - on to the vacuum leaks.

Dennis Wilson

Jay is right about the top vacuum line going to the TB right side front port. The vacuum lines are both needed to provide enrichment during WOT and deceleration to keep the engine from backfiring.

Backfiring can also blow the seal/gasket out between the two halves of the lower intake plenum. The fastening bolts should be spring loaded to function like a popoff valve. A visual check should be made by removing the upper plenum and air filter housing and looking for pieces of protruding gasket around the lower plenum. The hoses connecting the upper plenum to the spiders can also blow out during backfires. For some reason (contamination?) the bottoms of these hoses are where the leaks occur.

Dennis