- Rep Power
Replacing your fuel pulsation damper
(First things first: many dankes and salaams to Llamavan for taking the pictures, for being such a wise site administrator, for looking after my vans when I'm overseas, and for being an all-around good person.)
A couple of days ago I replaced the fuel pulsation damper (FPD) in my '87 4WD.
What, you may ask, are the symptoms of a bad FPD? The most obvious (and dangerous) one is a strong smell of raw gasoline in your engine compartment, outside the van, and possibly in your van's people compartment.
If you suspect a gas leak, pull over and stop and investigate the cause! Gasoline is very volatile, has a low "flash point," and will catch fire in less than a heartbeat! Safety first, last, and always - I cannot emphasize this point strongly enough.
If this job description seems overly detailed to the point of being patronizing, I apologize in advance. I supervise the maintenance and operation of a merchant ship's engineroom for a living, and am accustomed to giving explicit step-by-step instructions in most aspects of the jobs done by those who work for me.
Prepare for the maintenance before you start turning wrenches. When you remove your FPD, you will inevitably lose some gas out of the fuel rack (pipe) that supplies the injectors. Your van's exhaust manifold (below the FPD) should be cool to the touch before starting. Make sure the space where you replace your FPD is well-ventilated (preferably outdoors), and you have some method of controlling or containing the fuel that will spill.
You will need a 22 mm open-end wrench for removing and reinstalling the FPD, and a wrench for disconnecting your battery cable. You need not remove the passenger-side engine cover. There are two types of FPDs for our vans; my '86 and '87 take part number 23270-50011 and my '88 takes P/N 23207-16020. Check with your parts source to see which one fits your van, based on your VIN. The gaskets needed for the FPD are the same for all years; they are P/Ns 23232-41081 for the aluminum gasket on the FPD and 90430-12005 for the copper gasket between the banjo fitting and the fuel rack. You will need one spare of each type of gasket per FPD replaced; they should not be reused. More on gasket location and fitting later.
To cut down the fuel pressure behind the FPD before removing it, you can try running your engine while removing the 15 amp EFI fuse. This picture shows the location of the fuse, right next to the main fuse box under the dashboard, circled in red:
FPD 1a comp. EFI fuse removed.jpg
My engine stopped as soon as the EFI fuse was removed; YMMV.
Once your van is in position for the work, it's a good idea to block the wheels. Next step - remember, safety first - is to disconnect at least one of the battery cables. Now you can start removing the FPD. This picture shows its location, circled in yellow, below the throttle body and intake manifold:
FPD 2a comp. FPD before highlighted.jpg
Note the two clamps on the adjacent vacuum hose that have been moved for ease of access. Having skinny fingers and small hands helps when doing this job.
Once you loosen it, the FPD should screw right out. This is the aforementioned point where you will lose some fuel. If you have to put a bit of muscle into loosening the FPD, make sure you brace the fuel rack to prevent fracturing it.
This picture shows the copper gasket (P/N 90430-12005) and banjo fitting above the FPD when it is removed:
FPD 6a comp. FPD Removed.jpg
This picture shows my used and new FPDs. Note the absence of the machine screw in the top of the old one:
FPD 5 comp. Both FPDs.jpg
Now, with the new FPD turned upside down, place a new aluminum gasket (P/N 23232-41081) on its threaded shaft. Remove the old copper gasket from the banjo fitting, clean the banjo fitting's gasket seating surfaces as best you can, and then place a new copper gasket between it and the fuel rack. Getting the gasket centered on the banjo fitting opening is not critical at this point; when you push the FPD into the bottom of the banjo fitting, the gasket will be centered by the shaft. (Just make sure that the gasket does not fall out during the replacement.) You may have to tug a slight bit on the banjo fitting to get it up into its slot on the bottom of the fuel rack.
When threading the FPD into the fuel rack, be careful not to cross-thread it, or you'll wind up replacing the entire rack. It should thread in easily, once you get it all oriented properly. Using your handy-dandy 22 mm open-end wrench, tighten it until it's snug - don't make it too tight. This picture shows how the new FPD should look once it is installed and tightened:
FPD 7 comp. New FPD Installed.jpg
OK, you're done with the installation. Let it sit for a little while to allow the gas fumes to dissipate, then reconnect the battery. If you removed your EFI fuse, now is the time to reinstall it. It's a good idea, but not absolutely necessary, to use the fuel pump to fill up the fuel rack and check for leaks before starting. To do this, locate the fuel pump check connector near the air filter and throttle body. Short out the two connections in it (safety first - use insulated wire!), then turn your ignition key to the "Run" position. You should hear a relay click and the electric fuel pump start. It will take just a few seconds to fill up the fuel rack. If you spot any leaks, shut down immediately and troubleshoot!
Turn the ignition key to "Off" and remove the fuel pump check connector jumper. Check your work one more time to make sure everything is back in place. With the "hood" still open, start your engine and check again for any fuel leaks; increase engine RPM to the normal range and check again.
If you have no fuel leaks, sit back with a cold one of your choice and enjoy the satisfaction of a job well-done. B^)
Last edited by Flounder; 12-26-2010 at 11:53 AM.
Reason: Better pictures
Re: Replacing your fuel pulsation damper
Thanks for the awesome write-up Flounder! Very impressive documentation. It cannot be stressed enough the importance of safety here. Like Flounder said, anytime you smell raw gasoline it should be investigated immediately. These FPDs are a common leak point on these vans and I know of several vans that have burned due to a leaky FPD. One of these vans was the white one I wrote up HERE in my body work thread.
The leak started after I sold the van. The new owner noticed the gas smell but kept driving (did not investigate). A week or so after that the van went up in flames (total loss). It was parked next to his 95 SC All-Trac Previa and that was also lost . Fortunately his losses were limited to these 2 vehicles, but it could have been much much worse. We will never know the exact cause of the fuel leak, but his Fuel Pressure Regulator (FPR) was less than 1 year old so I suspect the FPD. Had he investigated this ASAP, these vans would most likely still be alive. Tim