Post by thomash on Nov 5, 2004 16:57:43 GMT -5
As part of assessing whether my fuel pump was working, I decided to build a fuel pressure gauge. This will work on the 3S-GE and probably other models as well.
Why build a pressure gauge yourself? I checked some auto parts stores -- Pep Boys, AutoZone and Advance Auto -- and the fuel pressure gauges they carried (if they were in stock) were only for models having a Schrader valve on the fuel rail, something Toyotas don't have. Moreover, for the high pressure models (needed for fuel injected engines), the price was around $40 in my area.
Parts needed (can be found at Ace Hardware and/or auto parts suppliers):
- Pressure gauge, 0-100 psi -- around $5
- Coupler for two female 1/4" NPT pipe fittings - $2
- Female 1/4" NPT to 5/16" hose barb - $2
- 5/16" fuel injection hose - $5 per foot
- 5/16" hose clamps - $2
- 8mm / 1.0 mm pitch bolt, at least 30 mm in length
- 8mm / 1.0 mm pitch nut
- Teflon tape
You will need to cut off the head of the 8 mm bolt with a hacksaw, and then drill out the bolt through the middle. A small drill bit will be okay -- for example, 1/8" or 3/32". This is best done in a bench vise with a new bit, but a pipe wrench or large vise grip might suffice.
Connect the coupler to the pressure gauge and the hose barb to the coupler. Connect the hose to the barb with a clamp.
Remove the bolt supplying the cold start injector on the fuel rail. You will need to replace the copper crush washers. Set cold start injector pipe aside. Wrap bolt with teflon tape for sealing and thread up to about 10 mm through a copper washer and nut and into the hole. Tighten the nut. Finally connect the pressure gauge hose to the top of the bolt with a hose clamp.
This procedure/idea is documented in the Haynes manual, but several important facts are omitted:
- You need an 8 mm bolt with 1.0 mm pitch. 1.25 mm is the more common thread pitch, so don't mistakenly choose the wrong one.
- A "fuel pressure gauge" is harder to find, more expensive and probably not worth buying since it doesn't have an adapter
- 5/16" hose is closest to the 8 mm bolt size and will make a good fit
- Drilling out the bolt isn't fun and probably will dull your bit, but finding a banjo fitting like what is on the cold start injector pipe isn't easy. The cold start injector pipe is sold as an assembly for $20, so you could possibly buy that and cut off one end to attach to the gauge (probably needing a different hose barb).
Why build a pressure gauge yourself? I checked some auto parts stores -- Pep Boys, AutoZone and Advance Auto -- and the fuel pressure gauges they carried (if they were in stock) were only for models having a Schrader valve on the fuel rail, something Toyotas don't have. Moreover, for the high pressure models (needed for fuel injected engines), the price was around $40 in my area.
Parts needed (can be found at Ace Hardware and/or auto parts suppliers):
- Pressure gauge, 0-100 psi -- around $5
- Coupler for two female 1/4" NPT pipe fittings - $2
- Female 1/4" NPT to 5/16" hose barb - $2
- 5/16" fuel injection hose - $5 per foot
- 5/16" hose clamps - $2
- 8mm / 1.0 mm pitch bolt, at least 30 mm in length
- 8mm / 1.0 mm pitch nut
- Teflon tape
You will need to cut off the head of the 8 mm bolt with a hacksaw, and then drill out the bolt through the middle. A small drill bit will be okay -- for example, 1/8" or 3/32". This is best done in a bench vise with a new bit, but a pipe wrench or large vise grip might suffice.
Connect the coupler to the pressure gauge and the hose barb to the coupler. Connect the hose to the barb with a clamp.
Remove the bolt supplying the cold start injector on the fuel rail. You will need to replace the copper crush washers. Set cold start injector pipe aside. Wrap bolt with teflon tape for sealing and thread up to about 10 mm through a copper washer and nut and into the hole. Tighten the nut. Finally connect the pressure gauge hose to the top of the bolt with a hose clamp.
This procedure/idea is documented in the Haynes manual, but several important facts are omitted:
- You need an 8 mm bolt with 1.0 mm pitch. 1.25 mm is the more common thread pitch, so don't mistakenly choose the wrong one.
- A "fuel pressure gauge" is harder to find, more expensive and probably not worth buying since it doesn't have an adapter
- 5/16" hose is closest to the 8 mm bolt size and will make a good fit
- Drilling out the bolt isn't fun and probably will dull your bit, but finding a banjo fitting like what is on the cold start injector pipe isn't easy. The cold start injector pipe is sold as an assembly for $20, so you could possibly buy that and cut off one end to attach to the gauge (probably needing a different hose barb).
