Fuel Pump Problem....or Not? (AKA Quits when Hot)

When an engine quits running, it is common for folks to suspect a fuel pump problem. After all, enough LD'ers have had that experience.

But....while a noisy pump often indicates a problem it doesn't necessarily mean you have found the problem. There are other parts that would can cause the engine to stop running that are also heat sensitive, failing only when hot and working again, once cooled. The two most likely items of a ignition system of older LD's are the ignition coil and ignition module.

Heat related failures are very hard to troubleshoot, you need to be able to quickly check for spark, fuel pressure and pulsed power to the injectors, at the time of failure. Without actually checking it when it will not start, it's an educated guess.

Back in the good old days where a lot of parts needed frequent replacement.I carried a spare coil, ignition module and a full tune up kit.

Now to help troubleshoot problem with the LD, I carry a fuel pressure gauge, a wireless spark detector and fuel injector noid lights (used to check the fuel injector circuits).

Many times a faulty part will set a Check Engine light (CEL).  An inexpensive code reader, one capable of erasing codes, is very helpful to have. You need to have a list of what the codes mean or an internet connection to check online. I have found a lot of ScanGauges and UltraGauges that will not erase Check Engine codes, where a code reader will.

Add to the box a 12-volt test light and a decent multimeter, the type with a clamp-on amp meter is useful for a whole range of troubleshooting.

With these basic tools and proper knowledge you have a good chance of finding what part of the equation is missing.

Working with engines, gasoline and electrical can be dangerous so if you do not have the proper training or experience, let a pro do it or find a good teacher. It's cheaper than going to the hospital.

Think your fuel pump isn't working or it suddenly stops, the fuel pressure gauge can let you know if it is providing adequate pressure, which need to be within a few PSI of the set point.

The pump does not require that the engine is running to be tested, only the ignition needs to be turned on.

When attaching the gauge, have the ignition switched off. Hold a rag around the connection point to capture any gas that may still be under pressure and spray out. Safety glasses are a must.

Please stay safe or find an experienced mechanic. Try this at home so you know how it's done before needing to use it on the road. Also find the specified fuel pressure for your engine's fuel pump.

Besides helping to find a defective pump, the fuel pressure gauge can also help find leaking injectors and check valves.

http://www.harborfreight.com/fuel-injection-pump-tester-92699.htmlhttp://www.harborfreight.com/fuel-injection-pump-tester-92699.html

Many newer engine have the coils mounted right on top of the spark plugs, also known as COP, coil on plug. This arrangement makes it impossible to use a conventional inline spark tester.

The LD's V-10 has COPs that cover most of the access to the spark plug. They do have slots where the thin tip of a wireless spark detector can be fitted.

I use one of these. It's sensitivity is adjustable, a handy feature as every engine seems to have a different physical layout requiring more or less sensitivity.

With someone cranking the engine, check for spark at one or more plugs.

Practice at home so you have a good idea where the best spots are to test for spark and how to adjust the sensitivity. Actually, the V-10 is hard to access when checking for a heat related failures, because of the difficulty of removing the doghouse quickly, needed to access the rear eight plugs. It you look and tie things back, you can access the front two plugs and injectors from under the hood.  Coils do fail, so carrying a spare is't a bad idea. A bad coil will usually set a specified code for the cylinder.

 http://www.amazon.com/gp/product/B000JFHMPC?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00http://www.amazon.com/gp/product/B000JFHMPC?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00

If spark and fuel pressure are present, then test the fuel injector circuits for pulsed signals. Use the proper size "noid" light for your injector's plug. Noids are are small lights, that plug into fuel injector plugs, once uncoupled from the injector.  They test the fuel injector circuits for pulsed signals, when the engine is cranked or running. They are useful for finding a dead ignition system, a failed injector or a failed injector circuit.

My fleet contains four different sized fuel injectors plugs so it was cheaper to buy the big set and keep the extras for the future.

 http://www.amazon.com/gp/product/B000YF6TN8?psc=1&redirect=true&ref_=oh_aui_search_detailpagehttp://www.amazon.com/gp/product/B000YF6TN8?psc=1&redirect=true&ref_=oh_aui_search_detailpage

If the engine is running but is either making noises or missing, an inexpensive mechanic's stethoscope can be invaluable. You can listen to individual fuel injectors, Comparing them each other. A dead or stuck injector usually makes a much different noise. You can isolate noisy bearings and eliminate changing the wrong part. Be extremely careful to stay far away from the moving belt and pulleys, they remove fingers quickly.

Even good parts can make strange noises, it's good to know what "normal" sounds like.

http://www.amazon.com/Powerbuilt-640582-Mechanics-Stethoscope/dp/B004KEHGZY/ref=sr_1_1?s=automotive&ie=UTF8&qid=1455164440&sr=1-1&keywords=mechanic+stethoscopehttp://www.amazon.com/Powerbuilt-640582-Mechanics-Stethoscope/dp/B004KEHGZY/ref=sr_1_1?s=automotive&ie=UTF8&qid=1455164440&sr=1-1&keywords=mechanic+stethoscope

For all the test tools above, the internet has hundreds of sites and videos that explain how the various tools and systems being inspected work. Above all, work safely.

Contributor: Larry Wade

Published: 11 Feb 2016

Fuel Pump Shut-Off Switch (Inertia Switch)

No fuel to your engine? A good number of us are probably familiar with Ford’s fuel pump issues and have had to go through the replacement process.

Well, it seems there is another item that could mimic a non-working fuel pump. It’s called an inertia switch or fuel pump shut-off switch, and is designed to cut off the flow of fuel in the event of an accident to prevent fire.

The switch has a magnet inside that holds a steel ball up, if there is sufficient impact to knock the steel ball loose the fuel pump is shut off. If this switch should somehow get triggered or in some way malfunction, you would find yourself with no fuel getting to the engine.

A dishonest mechanic or service writer could exploit the inertia switch to sell a new pump install, or worse still, charge you for a pump install that doesn't really take place. This scenario is tougher for the shop when you ask for them to give you back the replaced parts. They may or may not have a spare old fuel pump to give you, in that case. 

So, you ask, where is this switch located? 

                                                                             

It can be located in two different locations, behind the passenger foot well kick panel, or in a bracket above the brake pedal.  The passenger footwell location seems to be the more common. It is located in the passenger side footwell, under the plastic trim piece. The trim is held on with spring clips and pops off. The switch doesn't look like much, similar to a plastic plug.  On top of the switch there is a hole in which the red reset button resides. When in the 'on' position, the button is recessed and not visible. When tripped, the button pops out. Pushing the button inward, resets the switch. On some vehicles it may not be necessary to pop off the trim piece – there may be a little hole or notch in the trim through you can put your finger to push the red button in to reset the switch. The red rubber reset button, about the size of a quarter,  is located about 90 degrees from the face of the panel and slightly below the cutout. You should be able to feel around and locate it.

If resetting the switch does not solve the problem, check the fuse: Power starts at fuel pump fuse #17 in engine fuse panel out as yellow wire to fuel pump relay, out of relay as dark green wire to inertia switch, out of inertia switch as pink wire to fuel pump.

Contributors: Larry Wade, Kevin Lindsay, RonB, WxToad, Delta Mike

Updated: 28 Sep 15

Fuel Pump

In most modern vehicles the electrical pump is not exposed at any fuel level except absolutely empty. It's located in a "fuel delivery module" (FDM) which houses the pump in an enclosed plastic reservoir. The pump output not needed for fuel delivery is redirected to power a venturi jet pump which draws in gas from the tank regardless of fuel level. This jet pump keeps the reservoir completely full most of the time, and the flow used to power it maintains consistent fuel flow through the electrical pump in times of low demand to maintain cooling. The reservoir is only drawn down during the few moments before pump pressure drops below the threshold needed to keep the engine running. Even then, there is still some flow through the pump, it just sucks enough air to prevent it from pushing it all the way to the injectors.

This is also what keeps your engine running if you go around a corner quickly, or up a steep hill, when the tank is low. The bulk of the fuel sloshes to the back or side, but what is trapped in the FDM continues to provide fuel until a more normal attitude is restored.

Another common one I see on the internet is "don't run it down because it will suck in stuff from the bottom of the tank" but that FDM reservoir intake is pressed against the bottom of the tank - in fact, it is spring-loaded to insure it is ALWAYS pressed hard against the bottom of the tank. In other words, it always draws from the bottom, regardless of fuel level. There is a mesh cloth filter (usually called a "sock")on the jet pump inlet to catch any crud, and often a screen on the bottom of the electrical pump as well.

If you are really interested for some reason, googling "fuel delivery module" will bring up diagrams of how it's all put together. The general design is fairly universal across manufacturers.

That being said, there are those who feel that when you run your tank low on fuel, your fuel pump may not be covered by the fuel. That can cause the fuel pump to overheat and that can lead to early fuel pump failure. This has been advised by Click and Clack and Ford mechanics.

One indicator of impending doom, so to speak, is the lighting of the Check Engine light. If you have a ScanGauge installed or have some other method of reading the output of your OBDII socket, you'll probably see a Diagnostic Trouble Code of P0190, Fuel Rail Sensor. If you don't have a way to read the OBDII output, your mechanic will be able to. At first the Check Engine light will come on sporadically, but will increase in frequency over time. The risk is that sometime, somewhere, where you least expect it, the pump will fail for good, leaving you stranded.....hopefully not out in the boonies.

In addition to all the above, there seems to evidence that there is a defect in the new fuel pumps and that Ford is aware of it. A Ford dealer has told one owner that this is the case, but Ford apparently has not notified any users.
Replacing the fuel pump is expensive - the gas tank must be dropped to obtain access to the pump. That in itself is a major part of the roughly $1500 cost of the pump replacement.
You may be able to reduce the cost considerably by getting the fuel pump yourself and having the installation done at an independent garage. This is what Alex Rutchka did when his pump died while in Alaska. He ordered the pump, Airtex E2437S (for 2005 Ford E-450 Econoline 6.8L 415 cid V10 FI) from www.RockAuto.com. The pump plus shipping to Alaska was $270 and the installation labor charge was $400.

If you have the right tools and equipment, you can tackle the job yourself (assuming you're at home and not on the road). You can get the fuel pump (DELPHI FE0298) and fuel strainer FSO127 from NAPA or a Ford dealer. Air tools will help, as will a big floor jack with which to lower the tank. One RV'er who took on this job says he got it done in a weekend. The fuel pump itself was quite easy to replace, getting to it was not much fun. The hose clamps were rusted on the fuel filler lines and had to be replaced.

The pump used on fuel injected trucks had a design flaw. In '97, they changed the design. You need to use a '97 pump if you want a permanent cure. The electrical connections on the newer
pump won't fit your truck, so they sell an adapter kit for it.
Contributors: Steve Kocan, Ron, Alex Rutchka, Darrick, Nels, Victor Sanchez, WxToad

Revised:12 Oct 13

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