Automotive Fuel Filter Driveability Problems
This is not really a case study but more of a thought of mine that I would like your input on. I have replaced countless fuel filters in my short time of only 7 years as a technician. I replace fuel filters when I do a tune-ups, as a maintenance item, because of a customer request and when replacing fuel pumps. When I first started, I also replaced fuel filters thinking I might fix a driveability issue. This post is about how many fuel filters have fixed your driveability problems. How many of you out there have replaced a fuel filter that has truly solved your driveability problem? Besides carbureted vehicles I can only remember one vehicle that a fuel filter fix my problem. The problem vehicle was a late 80′s Ford F-250 with the dual tank setup. It had the regular style Ford fuel filter and also the cartridge type fuel filter that is in a canister on the frame rail. The cartridge fuel filter was the filter that was cutting my fuel volume down on this truck, causing high rpm miss, surge, and lack of power.
Almost every driveability class I have taken always point at the fuel filter as one of the first items to check. Customers always want there fuel filter replaced when they have a driveability problem of any sort. A lot of trouble trees point at the fuel filter as one of the first places to check. Is all of this a carry over from the carburetor days? Maybe I have just been fortunate or misfortunate for not seeing any? What do you think? Email me at dewitzauto@dewitzauto.com. Please include some information about yourselves if you want. I will post some of the responses I get.
I would love to hear how many people are on my side of the fence or the other side. I know fuel filters could easily be the cause of fuel issues, but it seems like electric fuel pumps have a way of dealing with it. A lot of pumps dead head over 100 psi so I suppose there is a lot of push if needed to get through a plugged filter. I’m sure you all have pulled off a filter, tried to blow through it and wonder how this car even ran let alone run with no issues what so ever. It would be neat to put a pressure gauge before and after the filter to see if you could see a difference in pressures on a test drive caused by a plugged filter.
A lot of people say you can see a plugged filter by watching the fuel pump amperage. I believe this is true on certain vehicles and pumps. I have seen proof (from a video) that a restriction in the fuel line may only increase the pump amperage as little as 1/2 an amp at a Visionstraining class. The only way you will catch this, is by doing a before and after amperage reading when changing the filter. That kind of defeats the purpose of the amperage reading in the first place, if you were looking for a plugged filter with it. There are really no exact stated amperage readings either, just ranges that vary 2 amps or more. An example would be pump that draws 4-6 amps in which a restricted filter is causing a 5 amp draw instead of 4.5 amp draw. I’m not going to catch that, how about you.
The bottom line for me is, if the fuel pressure or volume are low, I may check the filter. I will change the filter like I have been for tune-up, maintenance, customer request, and after fuel pump replacement. I feel that the worse thing that a plugged fuel filter is actually going to do is damaging a fuel pump long before you ever have a problem. The problem you will eventually see will be a dead fuel pump before a driveability issue arises, in most cases. What do you think?
update 3/16/2008 Here is a plugged fuel filter that caused a driveability problem. No pressure issues at idle, but had low volume.
4 comments
Like you have stated, I have found only one fuel filter that affected driveability and only when vehicle at around 45mph. It was also a Ford; a 1987 Bronco 2, 2.9l. It idled perfected but had a slight skip/stumble at around 45 mph that bugged the owner. When I had it on the lift, I noticed the original fuel filter in the LH rail. Ford manual says this filter does not need to be changed… I replaced it and the problem went away.
Maybe it just a Ford Truck thing???
Jay
We need to diagnosis this problem just as we would any automotive issue, in the seven years you have just begun . Lets look at the big picture fuel filter issues or issues caused by fuel filters? clogged fuel injectors low fuel pressure melted wires relay issues drivability problems. Back in the seventy’s we had a filter, pump or tank screen clogged and it felt like a clogged cat. Today we have low fuel pressure because of a filter especially with flex fuel where the regulator can be in the filter or a clogged injector the dirt got there threw the filter and o yes the screen in the tank after 30,000 miles its useless so now the filter is even more important. I change the filters more now than ever just to prevent problems, every twenty five thousand i change them and shame on the manufactures that put them in the tank and can not be changed. Even though we are in the electronic world of car repair and diagnostics lets not forget that fuel is to, as spark is to, as compression is to, the very beginning of operation In my 44 years of being a automotive technician you not only look in the future for p&m needs but diagnosing a troublesome car sometimes you have to look back in order to find the problem. Good luck in the future and make sure you always address yourself as a Technician for they are more than just mechanics.
I hardly replaced a fuel filter in the first 30 years of motoring. Just didn’t need to. I’m presently driving an 80′s carburettor Toyota and I’m replacing filters as a necessity all the time. The car starts to miss and loses power going uphill. It gets worse quickly and within a week it is impossible to drive it.
I’m using unleaded fuel and inputting a lead based octane booster. If too much additive goes in the filter blocks after a couple of days. Last time I drained half the tank and filled it with unleaded without additive then replaced the filter.
Fuel filter on a carbureted vehicle are a completely different story. They use mechanical or low volume pumps and filters are smaller. I have no idea why additive would make a difference but I’m sure an 80′s vehicle may have rust and debris in the tank.