I want test my fuel pressure. What is a good gauge or kit to buy? My truck has lost power towing and is now starting to miss a little. I'm wandering if i my problem is in the tank. Is there a good scan tool that would help diagnose things too? Thanks.

 

Fuel pressure is not reported by any sensors, so a diagnostic tool will not help in this case.

You can get an adapter for the fuel bowl from DieselOrings, and you will need to get your own fuel pressure gauge; one with a long hose is preferred.

Here is a video that shows how to do it. In the video I use a short fuel pressure gauge, so I cannot monitor the pressure from the cab. In cab readings are essential, and the video is really just for demonstration. The best way to measure fuel pressure will be while driving under acceleration, a parked test will not always reveal a problem.

There is no pump in the tank luckily, however there is a small screen to act as a basic filter to protect the pump. This screen can clog and reduce fuel flow to the engine. I dont have a video on how to fix this, however a permenant fix requires dropping the tank. A temporary fix can sometimes be achieved by blowing some low pressure compressed air in the tank by disconnecting the line at the fuel pump.

 

Thanks for the reply. I'm familiar with the in tank mods. Just don't want to drop the tank if I don't have to. I'm more interested in the gauge itself. Will a kit from auto zone work ? Or will I need something specific for diesel? I'm also considering a scan tool. Just wanted to know the good ones and those to stay away from.

 

A kit from autozone will work, just be sure you have the right fittings, and the gauge goes up to at least 100psi, and the gauge should be rated for diesel.

As far as scantools, you can get the $50 orange OBD II scan tool they sell, which will pull some codes, but not all of them. My truck is a 2002, and as I understand it after 2001 some PCM changes were made and more codes were OBD II compliant, so mine has always worked for me, and I can clear most codes.

However, a good scanner will be able to communicate both ways with the truck including diagnostic tests. For this, I recommend the AutoEnguniety. Which I have almost certainly spelled wrong.

 

Thanks that's what I need to know. Are scan tools good for any vehicle? Or are there some for diesel only?

 

Fuel Pressure Test:

Tools: Fuel Port Adaptor (M12 1.5) and Pressure Gauge 0-160 PSIG. I have a 15 Foot Hose I assembles from a 3/8" Air Hose and some couplers / DVOM

** Fuel Bowl Test Port Spec. 45 psig min See 8c. below

8b. Right Head:

a. Fuel Pressure at the right head Verify that fuel is in the tank and the pump is being powered.

b. Measure fuel pressure at the front of right cylinder head Road Test- engine at full load condition Spec. Measurement / Head 0-160 PSI /
WOT 45 PSIG min.

c. If fuel pressure fails low, go to step 8c.

*If pressure is above min. spec, go to step 8b.

d. Fuel Pressure at the left head Measure fuel pressure at the front of right cylinder head Road Test- engine at full load condition Spec.
Measurement / Head 0-160 PSI / WOT 45 PSIG min.

CAUTION: Secure hose away from turbo and exhaust If fuel pressure is below min. spec, replace left check valve If fuel pressure is above
min. spec, * Go to step 9.

8c. Electric Fuel Pump

a. Measure Fuel at Fuel Bowl Test Port using Fuel Port Adaptor (M12 1.5) and Pressure Gauge 0-160 PSIG / DVOM Spec .45 psig WOT >42 psig

b. Measure at fuel outlet from electric fuel pump: Engines built since 1/1/98 or engine serial #661496 should be 51 ± 4.5 PSI @ idle.

c. Road Test- engine at full load condition 42 PSIG MINIMUM*

d. If fuel pressure fails low, go to step 8d.

e. If pressure is above min. spec, replace right check valve.

8d. Electric Fuel Pump Inlet Restriction

a. If fuel line is restricted above 6 Hg, check for: blockage between pump and fuel tank.

b. If fuel line is not restricted, inspect regulator valve condition and for debris, If OK replace pump

*Testing Procedures on all 7.3 DIT 1999.5-2003 F-250-F-550 Models*

 

Three things that have proven invaluable time and again with our aging fleet:

• EGT gauge (one side or both)
• Fuel Pressure Gauge
• Scan tool or gauge.

I have both EGTs, fuel pressure (gauges are ISSPRO EV2 from Riffraff Diesel) a scan tool (AutoEnginuity) for troubleshooting, and a scan gauge (Torque Pro) for monitoring everything during my normal drives.

 

Just my 2 cents: I think the aftermarket, in-cab fuel pressure gauges are not very reliable. i have gone through SO many of the pressure senders. I don't think they are made for high pressure fuel systems like ours. They are always warranty covered, but it is still a hassle to replace the sender with a plug and wait for the new one to arrive. I have used ISSPro and Autometer gauges. I just ordered a liquid filled gauge from Northern Tool that is supposed to be accurate and durable, but it will go under the hood, not in the cab. I will report how it fares.

 

So how are they failing? Are they actually breaking to where they leak? I have about 4 years on my isspro with no problems, maybe I should dig out a plug and put it in the glove box?

 

They eventually leak and stop working. Sometimes they kind of melt/deform. Always covered by warranty but a hassle. I have a plug in the glovebox. The thing is, my sender is in a port in the head, because I have deleted the fuel bowl. So its a more inconvenient to remove.

 

Honestly, this sounds as though it is a "Quality Issue". Senders can vary from literally $2 - $200 - I'm not saying you need to buy the $200

As for the wiring, wiring can be purchased rated for heat disbursement and isolation.

So, in the end, a Quality Gauge, Sender, and Appropriate Wire would provide a life long trouble free process so long at it is installed correctly and calibrated.

Bottom Line - You get, and benefit from what you pay for!

 

I have tried the $200 IssPro EV and a $100 autometer. I also have bought the pressure sender that goes with my ScanGauge. Maybe my truck has "pressure spikes" that kills the senders.

 

I may have found your problem. By installing the sensor in the head, you are subjecting it to temperatures in excess of 210-220 degrees F on a regular basis. I don't know if they were ever engineered for that. They were engineered to go on a fuel line, with a steady flow of warm fuel (not hot) cooling the apparatus the sensor fits into.

One other possibility with your sender location: Is your cooling fan occasionally making its jet engine noise when it's hot outside? If not, you may have a failed fan clutch - allowing your sensor temps to get much higher.

 

Your sig doesn't indicate new injectors, but it does indicate new fuel system. Did you delete the factory check valves where the original fuel lines entered the head?

Every time the split shot injector spills fuel back into the head fuel rail, it does so at 20,000 psi or so of injection pressure. Those pulses, multiplied by four injectors, multiplied by your RPM, without any check valve to block that chatter from the sending unit, might be too much of a handful for the sending unit to manage.

Have you considered a pulsation dampener, plumbed between your pressure sending unit and the fuel rail, to extend the life of your pressure measuring device?

 

Good info, Tugly. Could be.

I did not delete the factory check valves, like in a Frybrid style conversion. I have the greasecar conversion so the check valves are not removed.