I am in the middle (as in right now) of replacing my fuel pump with a 255 walbro for my 3800 SC swap and I need to know if I can use the stock "rubber coupler and sound Isolator" (name in the FSM) again or if it won't hold under a higher pressure. It is the piece inside the tank that goes between the top of the fuel pump and the bottom of the tin lid on the tank. If someone can reply asap it would be a huge help as I need to put the tank back in today.
Thanks, Dan
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11:41 AM
PFF
System Bot
Xanth Member
Posts: 6886 From: Massachusetts Registered: May 2006
I took mine out and replaced it with high-pressure hose. I didn't want to risk it leaking, even with just a stock pump. I have found no negative impacts from replacing it with hose.
The thing about the old coupler, is that it is old. I blew mine out, doing the part of the fuel pump test where you pinch the return line off.
That was on a 84 4 cyl tho, and as far as I could tell, the coupler/sound isolator was nothing more than a piece of rubber fuel line. Didn't even have clamps on it.
When I replaced my fuel pump, I looked at that hose (aka pulsator) and thought to myself "you gotta be kidding!" The hose (aka pulsator) isn't reinforced. At least, mine wasn't. The plastic "snap clamps" didn't inspire confidence, either.
It now has reinforced fuel line hose with metal hose clamps.
My advice would be to replace the hose now, so you don't end up replacing it later.
People seem to be confusing the pulsator with a hose. If it looks like a hose, generally having plastic hose clamps on the end of it then it is a hose. A pulsator has no clamps, is hard plastic and slips onto the pump and sender. It has lip seals inside. Some of the factory pumps used a hose, some used a pulsator. The pulsator is always the better choice over using a hose.
[This message has been edited by Electrathon (edited 04-06-2008).]
People seem to be confusing the pulsator with a hose.
Probably because some of us have never seen that gizmo. Mine just had the hose.
quote
If it looks like a hose, generally having plastic hose clamps on the end of it then it is a hose. A pulsator has no clamps, is hard plastic and slips onto the pump and sender. It has lip seals inside. Some of the factory pumps used a hose, some used a pulsator. The pulsator is always the better choice over using a hose.
Why is the better choice? Noise? I wanna be able to hear it run. What else does a pulsator do anyway?
[This message has been edited by maryjane (edited 04-06-2008).]
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05:43 PM
Xanth Member
Posts: 6886 From: Massachusetts Registered: May 2006
The Pulsator is a little flexible rubber chamber that connects the fuel pump with the fuel line. It was added to reduce noise and smooth out the flow. The trouble is that it is only slipped on the lines and uses no clamps. When the line pressurizes to 40-50 psi, as it gets older it will leak and you will lose fuel pressure. It is especially important to get rid of that thing when you do an engine swap and add a higher pressure pump. For a completely stock 2.8L it is probably fine but IMO it is a weak point and adds a potential problem area as the pulsator gets old.
------------------ 87GT - with 3800SC Series III engine, 4T65eHD 87GT - 3.4L Turbocharged engine, modified TH125H " I'M ON THE LOOSE WITHOUT THE JUICE "
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07:19 PM
PFF
System Bot
Firefox Member
Posts: 4307 From: New Berlin, Wisconsin Registered: Feb 2003
An easier way to understand what it does is to think of household plumbing. Have you ever heard a water hammer? Expansion tanks are installed to absorb the hammering that can happen in the plumbing. Pulsators are there to smoth things out in the fuel plumbing. It helps to keep a smoother, constant fuel preasure. Is it needed, absolutly. Is it mandatory, not at all. Many people are content with good enough. I have pulled hundreds of fuel pumps in the shop (GM had a lot of trouble with them a few years back). I have seen many failed hose lines between the pump and the sender. I have seen a few failed pulsators. Hoses fail far more often than pulsators, but both do fail. Removing a failed pulsator and replacing it with a working hose will definatly get a car back on the road, but is also not a proper repair. Just like in your homes plumbing. If your expansion tank failed, you can remove it. It will also work, just not a proper repair.
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07:52 PM
Apr 7th, 2008
fierosound Member
Posts: 15160 From: Calgary, Canada Registered: Nov 1999
You can also get a new fuel pulsator at any place that carries Dorman auto products (the HELP! packages). They can order it if you ask for Dorman PN 55160.
Why do some Fieros have the pulsators and some not? 99.9% sure I was the 1st person ever inside my fuel tank on the white 84, and it did not have a pulsator. Did 4 cylinders not get them?
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07:05 PM
Apr 8th, 2008
Electrathon Member
Posts: 5233 From: Gresham, OR USA Registered: Dec 2002
Why do some Fieros have the pulsators and some not? 99.9% sure I was the 1st person ever inside my fuel tank on the white 84, and it did not have a pulsator. Did 4 cylinders not get them?
The 4 cyl injection system uses less preasure than the 2.8 system, so a pulsator is less important. Also, GM was cheap and did not always use one. It was a trade off of cost savings verses quality. I can't count the number of bullitens that came out over the years telling us to install pulsators to stop customer complaints.
The hose that was used in the tank is also a special compound. It seems like junk, but it actually was fairly high quality. If you use regular fuel hose in the tank it will deteriate in a few years. The factory hose lasts far longer. Pulsators use silicone seals, so they last even longer.
[This message has been edited by Electrathon (edited 04-08-2008).]
