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Replace fuel pulsator

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Old Aug 3, 2016 | 09:03 PM
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Default Replace fuel pulsator

Hello,
Had strong fuel smell from rear of car. Car seemed like there was some type of fuel problem ? Can't really explain right now. Tried hooking up pressure gauge had problems, could not get reading , that's another story. I could be way wrong , but after visual inspection while car running. It looked like the pulsator was leaking fuel ??? I replaced with proper rated fuel line and car idles better and drives stronger . Right or wrong ? Pulsators sitting on work bench, see what happens ? Is there some type of check valve in the fuel system . So far everything seems ok ? Read somewhere here about fuel pressure and check valve ? Yes I don't know. Thank you.
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Old Aug 3, 2016 | 11:04 PM
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The check valve is in the fuel pump. If the pulsator was not connect to the lines tight, it could be leaking fuel so your getting little or no pressure to the fuel system. Replace the pulsator with a section about 2" long of high pressure fuel hose that can be submerged in fuel. Use screw clamps to attach the hoses to the fuel tubes in the tank.

Good luck on your Corvette Adventures.
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Old Aug 4, 2016 | 01:21 PM
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I just replaced my fuel pump. The new pump says it is a turbine style pump and does not require the pulsator (like the roots roller bearing type). It came with a piece of fuel hose to replace where the pulsator went.
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Old Aug 4, 2016 | 01:46 PM
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While its very possible, maybe probable, you have a bad fuel pump, a bad fuel pump will not cause a gas smell. Keep looking. You may have a bad hose or a requlator problem, or even a bad gas cap. The fuel pump is in an a sealed unit, the gas tank.

Last edited by zr1fred; Aug 4, 2016 at 01:50 PM.
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Old Aug 4, 2016 | 02:16 PM
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Originally Posted by zr1fred
While its very possible, maybe probable, you have a bad fuel pump, a bad fuel pump will not cause a gas smell. Keep looking. You may have a bad hose or a requlator problem, or even a bad gas cap. The fuel pump is in an a sealed unit, the gas tank.

Not sure about a regulator since it would suck the gas into the manifold and not throw it out the back where he is smelling it.
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Old Aug 4, 2016 | 03:59 PM
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There is a vent tube that leads to the charcoal canister that comes off the tank where the other fuel lines lines are by the filler neck. Maybe that line has a break in it or is plugged up causing the fumes back there.
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Old Aug 4, 2016 | 05:24 PM
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I've changed many a C4 Fuel pump and yet to reuse the pulsator. I always just go back and replace it with a piece of fuel line hose and have never had a problem eliminating it.
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Old Aug 4, 2016 | 05:45 PM
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Maybe a leaking gas cap?
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Old Aug 4, 2016 | 09:10 PM
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Originally Posted by aklim
Not sure about a regulator since it would suck the gas into the manifold and not throw it out the back where he is smelling it.
Thank you !!! Now that you said the regulator may suck gas into intake ? . A light sort of went on . I have checked the injectors numerous times for leakage, and never had any gas at vacuum line on regulator, however , I know it's obvious , But when I open the throttle plates by hand , I know this will sound funny. There is a gas smell from the intake that wound bring elvis back. It could explain so many quirks with the car . I may check it out this weekend.
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Old Aug 4, 2016 | 09:15 PM
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Originally Posted by skidball
Thank you !!! Now that you said the regulator may suck gas into intake ? . A light sort of went on . I have checked the injectors numerous times for leakage, and never had any gas at vacuum line on regulator, however , I know it's obvious , But when I open the throttle plates by hand , I know this will sound funny. There is a gas smell from the intake that wound bring elvis back. It could explain so many quirks with the car . I may check it out this weekend.
The system is batch fired so it will fire 1, 3, 5, 7 all at once regardless of whether it is being used at that instant or in the next few milliseconds. Possibly could be that some gas is unburned at the shutdown. It could also be your injectors leaking. Seeing as how long they haven't been cleaned (no, that does not mean sticking in snake oils in the tank), it could be leaking. Only way to tell is to take it out and have it put on a flow bench to test. Not sure what the years were but if you have Multec, they are crap.

Still, to verify what is going on, see if the system will hold pressure. Turn it to run mode and see what the pressure is and how long it holds.
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Old Aug 4, 2016 | 09:16 PM
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The gas smell is finally gone from the back of car, runs better, still more to check out. My backward thinking and I may be wrong ? Is that , if the gas in the tank was being disturbed and or the pulsator was leaking . You would have fumes, I know you will fumes anyway, it's a gas tank, That being a vented cap , and the spill tube on the car. Fumes maybe could happen ? That's my 2 cents.
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Old Aug 4, 2016 | 09:22 PM
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Originally Posted by skidball
if the gas in the tank was being disturbed and or the pulsator was leaking . You would have fumes, I know you will fumes anyway, it's a gas tank, That being a vented cap , and the spill tube on the car. Fumes maybe could happen ? That's my 2 cents.
When you don't open a bottle of soda and shake it around, do you smell the soda? The pulsator and the gas in the tank is sealed up. Either the vent hose is leaking or it is coming from somewhere else regardless of whether there are elves swimming in your tank or the pulsator is leaking.
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Old Aug 4, 2016 | 10:41 PM
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Originally Posted by aklim
When you don't open a bottle of soda and shake it around, do you smell the soda? The pulsator and the gas in the tank is sealed up. Either the vent hose is leaking or it is coming from somewhere else regardless of whether there are elves swimming in your tank or the pulsator is leaking.
Thank you for your reply. Have a nice day.
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Old May 22, 2025 | 03:30 PM
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Originally Posted by Klondike
I just replaced my fuel pump. The new pump says it is a turbine style pump and does not require the pulsator (like the roots roller bearing type). It came with a piece of fuel hose to replace where the pulsator went.

What year is your C5?
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Old May 22, 2025 | 04:19 PM
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The post is from 2016.
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Old May 30, 2025 | 12:40 PM
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My research seems to point to the fact that there is a fuel line check valve that is near the fuel pump that keeps fuel from flowing back into the tank after the key is turned to the on position just before a start. It is my understanding that this check valve also keeps pressure in the fuel lines, at least for a time, after the engine is turned off. Please let me know if you find out anything different. Some people seem to think that the valve is incorporated in the fuel pump on my 97 C5 but I determined that this is not the case.
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Old May 30, 2025 | 12:49 PM
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Originally Posted by tdoriausername
My research seems to point to the fact that there is a fuel line check valve that is near the fuel pump that keeps fuel from flowing back into the tank after the key is turned to the on position just before a start. It is my understanding that this check valve also keeps pressure in the fuel lines, at least for a time, after the engine is turned off. Please let me know if you find out anything different. Some people seem to think that the valve is incorporated in the fuel pump on my 97 C5 but I determined that this is not the case.
In a C4 the check valve IS part of the fuel pump. Dan
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To Replace fuel pulsator

Old May 30, 2025 | 12:49 PM
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The check valve may be located in the fuel pump on yours but my C5 is said to have the check valve in the fuel line that leads from the pump to the engine.
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Old May 30, 2025 | 03:39 PM
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Originally Posted by tdoriausername
The check valve may be located in the fuel pump on yours but my C5 is said to have the check valve in the fuel line that leads from the pump to the engine.
I did not know that Good info. Seems as if Chevy quit trusting the fuel pump check valves and decided to add a higher quality stand alone one in the line. Dan
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Old Jul 4, 2025 | 12:12 PM
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I have a 97 C5. Fuel check valve NOT located in the fuel pump. It is located in the fuel line that connects to the fuel filter/fuel pressure regulator.
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