Vacuum pump not coming on?

[QB93Z]

Originally Posted by Jeffvette

Jim, the hose you are pointing is the Fuel Pressure Regulator Hose.

Map sensor hose can't be seen from the top or side. Need to reach down and feel it.

Thanks Jeff. I was relying on memory and obviously, I was confused.

I edited the photo and removed the confusing label.

Jim

Originally Posted by QB93Z

Thanks Jeff. I was relying on memory and obviously, I was confused.

I edited the photo and removed the confusing label.

Jim

No worries. The fuel pressure hose is basically the same construction. Rubber ends with a plastic tube.

[1963korvette]

Think I found the source of the leak. PVC hose the larger hose had elctrical tape on it. When I pull it out it had a hugh tear. Ordered new setup from White Racing. Then pulled out the Vaccum Pump opened it up and there seems to be some corrosion not alot. How do I check it, would touching the terminal to a car battery work?
Thanks

[tomtom72]

Yes Rich, just fab up a two wire connection and use the battery. I had corrosion in my pump. I used WD40, some pencil erasers and a small brass brush and some contact cleaner to get rid of the WD40 as a last step.


Tom

[QB93Z]

The best test is to have the vacuum pump installed in the car and turn the ignition key to ON but don't start the engine. The vacuum pump should run for a few seconds and then shut off. You can hear it from the driver's seat, but if you have a doubt, have someone turn the key while you listen close to the pump. If the pump runs continuously or starts and stops periodically, then you have a vacuum leak in the secondary vacuum system. If the vacuum pump but doesn't make any sound, then it is faulty or you have an electrical problem.

Jim

[Hammer]

Vacuum pump from a Kodiak truck. Bolts on to a 91-95 ZR-1, but a harness adapter is available (according to Marc) or you could make one for a 1990.

https://www.partszoneonline.com/part...=&srch4=&srch5=

Original Pump part No. 15198448
Kodiak part No. 94669091

[cward]

Originally Posted by tccrab

The vacuum pump only assists the secondary system when the engine is at high rpms for an extended time.

TomC
"Crabs"

I am late getting this on but I was told by Graham B many years ago that the Yanks made them put in the vacuum pump for the very specific reason mentioned by Crabs. I did not have a vacuum pump on #364 and it ran just fine even at high rpms for an extended time. That said, I know that most Z owners will want the pump anyway. Just thought I would mention this in case you did not want to spend the money.

Curtis

[1963korvette]

Ok, fixed vacuum pump. When car warms up idle is about 1400 rpm, then every 20 sec drops down to about 800 rpms and it sounds like you are shaking a can with rocks in it. Can't see any other leaks I assume will have to pull pellum, but want to find out what I will be replacing first. Any thoughts?

[tomtom72]

Hummmm.....that's a new one. Okay Rich, so I make sure I get what you're saying: idle fluctuates between 1,400 & 800 on an almost even time frame?

Sounds like a fueling issue to me, or at least that's where I'd begin. In my mind, god that's a scary thought!.....the ECM is adjusting the pulse width to match O2 readings that are out of the expected "normal". That takes a bit of time to see the results of the ECM's changes if the injectors are at fault.

The rocks in a can noise is the dual mass flywheel reacting to the variations in force ( fuel ) in the suspect cylinders(s). It's kind of like a subliminal miss. It could be the injectors are going out to lunch. A scan to see the Block Learn numbers and the integrator numbers and the O2 numbers would seal the deal if there is a fueling issue. Those numbers are key to let us "see" what the injectors are doing in response to ECM commands, which are a reaction to what the ECM is seeing from the O2 sensors. The reason I say scan is that you said warmed up it does this stuff. Usually when theearly injectors have coil failure it shows up after the car is warmed up and gets worse the hotter the injector coil gets. You can do an OHM test thru the ECM harness plugs for the injector coils, that can also help in the diagnosis in the absence of a scanner.

If you stand behind the exhaust pipes can you smell anything? Rich or Lean smell? If you listen at the pipes do you hear any rich gurgling or lean pops?

Can you get a scanner with the right software to borrow? Do you want me to swing by & bring my stuff?


Tom

[tomtom72]

I need some help from the brain trust in my effort to help out Rich with his 90 Z.

I scanned the motor last night and got no DTC's, almost everything looked normal when compared to our "reference" page in section 6E with the data snap shot.

The car has a miss, or so it seems or like it's stumbling, but when you get into the secondaries past about the tip in point it runs fine, no stumble.

Here are some of the scan data in closed loop @ idle that I thought was not too great, and by the book it appears not to be too good either when I looked it up.

Block Learn enable = YES. book says it should be NO.

BLM cell = 16 ???? book says it should be 0 - 1.

Left BLM - 127 to 128
Right BLM - 136

Left Integrator counts were from 127 thru 133
Right Integrator counts were 126 thru 131

MAP reading in volts was 1.5 volts which is out of the book range of 6v to 2v.

I told Rich that knowing that the Air & fuel filters, plugs & wires & PCV's are new, to check the plugs for color, check that the spark is good. I'm not too sure about me laying blame for the stumble on the primary injectors.

Oh yea, his tach is about 1k rpms fast, how do you fix that?

TIA

Tom