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Discussion Starter #1
I am areal rookie at this. will try to give as much info as possible
95 corvette
was running but water leaking from water pump. it sat for about 6 months, battery was completely dead. I didn't start it just before replacing water pump.
replaced water pump. did not see any water on the opti spark. Put rag over it when pulling water pump.
engine now cranks over,
has fuel pressure (pushed schrader valve and fuel shot out)
has strong spark on at least one cylinder
can smell fuel after cranking
couple times it backfired when turned the key off.
i am looking for any ideas before sending it to the shop again.
 

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Discussion Starter #3
Did you reconnect pigtail your water pump sensor?


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i just checked it. I had forgot that. hooked it up and still nothing different
I am assuming that you are talking about the temp sensor.
 

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Have you put car on an obd 1 scanner, and scanned for codes? 95 f-bodies use a 16 pin aldl connector that looks like an obd 2 aldl with 16 pins, but is an obd 1 computer system. I'm assuming that corvette has the 16 pin aldl also.

You need to scan for codes because there are codes that don't light the check engine light. The 4 ignition biggies are among these codes. Dtc 16, & 36 are opti codes. Dtc 41 & 42 are icm related codes. All except dtc 36 will keep engine from running.

For fuel pressure check, pushing valve & watching fuel squirt don't cut it. You need a fuel pressure tester. Fuel pressure should be around 43 psi. Low fuel pressure or way high fuel pressure can keep engine from running.

When you checked opti for water, did you remove cap, rotor, & dust shield from opti and actually examine inside of opti? Water getting in will kill opti in short order.

To save new opti you might have to buy, drive a 90 degree tee fitting into weep hole of water pump. Silicon or epoxy around where tee gos into wp. Then attach hose to tee and route away from opti. That way when pump seal fails, opti won't take a bath.

If you end up replacing opti, only decent ones are GM, Delco, Delphi, or Msd. All but the Msd will be rebuilt units.
 

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Discussion Starter #5
In don't have access to obd1scanner at this point. That is the connector on it. Would the paper clip shorting show these codes? Will have to put the fuel pressure gouge on it.
I didn't open the opti since there was nothing on the outside. I assumed since it ran before and there wasnt water on the outside, it shouldn't be water issue. Guess I will have to take it all apart again if codes dont show anything.
The opti was replaced about 1 year ago. Hope that isn't it again.
Thanks guys
 

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Paperclip trick only works on 93 & older GM cars.

Unfortunately, if water has gotten on opti it has probably also went into opti. The water on outside will evaporate much quicker than what gets in opti. And the water will cause internal corrosion of the aluminum body and disc wheels. Also optical sensor electronics can get wet also causing shorts inside.

If you plan on keeping your 95 vette, you need test equipment. A digital multimeter, fuel pressure tester, & a PC based oscilloscope. They're about $70 on ebay, amazon, etc. A scope is only 100% way of checking opti low & high resolution signals.

Also good for checking that pesky 50 hertz fuel enable signal. The 2 opti signals and fuel enable signal are all square waves that need to be checked with a scope.
 

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Discussion Starter #7
Paperclip trick only works on 93 & older GM cars.

Unfortunately, if water has gotten on opti it has probably also went into opti. The water on outside will evaporate much quicker than what gets in opti. And the water will cause internal corrosion of the aluminum body and disc wheels. Also optical sensor electronics can get wet also causing shorts inside.

If you plan on keeping your 95 vette, you need test equipment. A digital multimeter, fuel pressure tester, & a PC based oscilloscope. They're about $70 on ebay, amazon, etc. A scope is only 100% way of checking opti low & high resolution signals.

Also good for checking that pesky 50 hertz fuel enable signal. The 2 opti signals and fuel enable signal are all square waves that need to be checked with a scope.
Thanks for the info. I will get the codes tomorrow and go from there.
It is my daughter's car so I don't plan on working on it much longer. It will be her problem. Did find something called torquehead conversion but it is expensive too.
 

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Discussion Starter #8 (Edited)
Found how to use paperclp for at least some codes.
Got: c12, h15,h74
15 is coolant sensor which I forgot to connect
74 is traction assist

Fuel pressure is 30psi guess that is next direction to go
 

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Years ago my fuel pump became weak, I was able to start car by “priming the fuel line;” I essentially would turn key to on (not start), back to off three times in a row, then car would start on 4th try (moving key to start). I eventually burned up the ignition switch (literally melted it) after about 6 months of operating this way. Only did it because I was in college and I had to save money for new fuel pump and was waiting for good weather to drop tank and drop in new pump. Grabbed new ignition switch and wire bundle from junk yard, but this little truck might at least get you started so you can move vehicle if needed


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Discussion Starter #10
bought a odb1 code reader. no codes showing but still won't start. replaced fuel filter and up to 34 psi. next step is fuel pressure regulator on Monday.
tried the repeatedly turn key and didn't work.
 

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I am areal rookie at this. will try to give as much info as possible
95 corvette
was running but water leaking from water pump. it sat for about 6 months, battery was completely dead. I didn't start it just before replacing water pump.
replaced water pump. did not see any water on the opti spark. Put rag over it when pulling water pump.
engine now cranks over,
has fuel pressure (pushed schrader valve and fuel shot out)
has strong spark on at least one cylinder
can smell fuel after cranking
couple times it backfired when turned the key off.
i am looking for any ideas before sending it to the shop again.
Check coil wire they have to be pretty long to make contact had same problem when I replaced plug wires put back on original coil wire fired right up
 

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Discussion Starter #12
have now replaced fuel filter, fuel pressure regulator and fuel pump. Getting 40 pi but still no fire. After repeated cranking get low o2on left bank code only. Looks like it is shop bound.
 

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I think there is another temp sensor in side of block (left) below exhaust manifold. Check for broken wire on that


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On a LT1 engine the important cooling temp sensor is on water pump. It tells pcm what coolant temp is. If your obd 1 scanner can do live sensor data, check cts temp. If it's way off actual coolant temp engine won't start.

Many times when a cts fails it tells pcm that coolant temp is either -100 degrees or reads hottest temp that it's capable of sending.
 

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If you bought really cheap obd 1 scanner, it's like shorting aldl leads with a paper clip and won't read codes on a 94 & newer LT1 equipped car.
 

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Discussion Starter #18
If you bought really cheap obd 1 scanner, it's like shorting aldl leads with a paper clip and won't read codes on a 94 & newer LT1 equipped car.
bought odb1 reader from 1320 eleconics. bluetooth to phone. they sent the aldl file to use.
 

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Discussion Starter #19
On a LT1 engine the important cooling temp sensor is on water pump. It tells pcm what coolant temp is. If your obd 1 scanner can do live sensor data, check cts temp. If it's way off actual coolant temp engine won't start.

Many times when a cts fails it tells pcm that coolant temp is either -100 degrees or reads hottest temp that it's capable of sending.
code reader gave coolant temp as 70F which was ambient temp
 
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